1) What is being quantified (and what is not)

These figures are scenario-based “GDP level differences” in 2035 (i.e., the size of the economy in 2035) relative to a Managed Rivalry baseline. They are not forecasts and they do not presume a single “true” model of the future. Instead, they are ranges anchored to published empirical estimates on geoeconomic fragmentation and then translated to UK-specific channels (trade, investment, financial services, risk premia).

Key anchoring datasets:

• UK nominal GDP reference level (for scale): IMF World Economic Outlook (WEO) DataMapper, “GDP, current prices” (indicator NGDPD).

• UK trade exposure to the US (goods): ONS partner article “UK trade with the United States: 2024.”

• Fragmentation cost ranges: IMF working paper and IMF F&D article summarising 0.3%–2.3% long-run global output losses under fragmentation scenarios and tail losses up to ~7% with fast, costly adjustment.

• UK financial-market centrality (rates derivatives turnover): Bank of England BIS Triennial Survey release showing 49.6% UK share of global OTC interest-rate-derivatives turnover (April 2025).

• Stress framing relevant to your scenarios: Bank of England Financial Stability Report (Dec 2025) and CCP Stress Test (2025) explicitly cite geopolitical tensions, fragmentation, sovereign-debt pressures as key risks/stress scenario elements.

• Financial/professional services macro importance: City of London “City Stats” factsheet (Nov 2025) and City statistics briefing (methodology cites ONS/TheCityUK etc.).

2) UK GDP impact by 2035: quantified ranges (level effects)

Reference scale: UK GDP today (for translating % into £/$)

The IMF WEO DataMapper lists UK nominal GDP around $4.23 trillion (WEO Oct 2025 dataset).
(That number is used purely to show order-of-magnitude of level effects.)

Scenario 2 (Baseline): Competitive interdependence / Managed Rivalry

2035 UK GDP level vs baseline: 0% (by definition)

But it is not “free.” This baseline assumes the costs of selective controls and “de-risking” are already embedded (compliance, some reshoring/friendshoring, higher capex in resilience). The Bank of England explicitly flags geopolitical tensions and fragmentation as key sources of risk—meaning persistent macro headwinds remain even absent a full split.

What characterises this baseline

• Fragmentation concentrated in frontier tech and strategic capital flows

• Trade continues broadly, but with higher friction and some re-routing

• Risk premia episodically spike around crises but don’t become permanent

Scenario 1: Structured New Cold War (Hard bipolarity)

2035 UK GDP level vs baseline: −3% to −8%

Why this range is defensible

• IMF research provides a central range for fragmentation scenarios of ~0.3% to 2.3% global output losses in the long run.

• IMF also discusses tail outcomes up to ~7% global GDP loss if fragmentation happens quickly and supply-chain adjustment costs are large.

The UK “hard Cold War” range is set higher than the IMF central global range because:

1. the UK is unusually exposed via cross-border services and finance (not just goods trade), and

2. a hard Cold War specifically targets exactly the UK’s comparative advantage: global market intermediation and compliance-bound capital flows.

Illustrative magnitude (using $4.23T reference level):

• −3% ≈ −$127bn

• −8% ≈ −$338bn

Core transmission mechanisms (UK-specific)

1. Trade & supply-chain fragmentation (goods + enabling inputs): a bloc split raises non-tariff barriers, forces rule-of-origin restructuring, and increases import costs and lead times (especially where Chinese inputs are embedded). UK dependence on major partners is evident in official trade reporting (example: US accounted for 9.7% of UK goods imports in 2024; Germany and China are also highlighted as top import partners).

2. Investment efficiency and productivity drag: duplication of tech stacks/standards, reduced technology diffusion, higher policy uncertainty (IMF channels: trade, capital flows, technology diffusion).

3. Financial-services fragmentation risk: if blocs push “local booking / local clearing / local data” rules, London loses some cross-border activity—hitting fees, wages, tax base (see section 3).

Scenario 3: Fragmented multipolarity (regional blocs, weaker global rules)

2035 UK GDP level vs baseline: −1% to −4%

This is typically less damaging than a clean two-bloc split because commercial flexibility remains: the UK can often keep trading and intermediating across multiple regimes. However, the cost is higher chronic volatility and greater regulatory complexity, which lowers investment and raises risk premia.

Illustrative magnitude (using $4.23T reference level):

• −1% ≈ −$42bn

• −4% ≈ −$169bn

What drives the hit

• Patchwork standards and episodic sanctions/export controls

• Higher global shock frequency (energy, shipping security, cyber)

• Repeated “risk-off” episodes that tighten credit conditions

3) Financial-sector exposure risk model (UK-focused, channel-by-channel)

The UK is not just a domestic banking system; it’s a global market platform. That changes what “exposure” means: systemic risks include market structure (clearing, intermediation, sanctions plumbing) as much as bank balance sheets.

Structural facts: why the UK is highly sensitive

A) London’s scale in global derivatives

The Bank of England reports the UK accounted for 49.6% of global OTC interest-rate derivatives turnover in April 2025 (largest centre globally).

Implication: fragmentation that changes where and how derivatives can be traded/cleared hits UK export earnings through volume and margin compression, not only through bank losses.

B) CCP centrality and explicit “fragmentation” stress design

The 2025 BoE CCP Stress Test report explicitly states its baseline market stress scenario focuses on rising geopolitical tensions, global fragmentation concerns, and rising pressure on sovereign debts creating conditions for a global slowdown.

Implication: the BoE already treats “your scenarios” as credible stress ingredients—so the risk mapping below is not hypothetical framing; it aligns with supervisory stress logic.

C) Macro importance of financial and related professional services

City of London’s published factsheet reports (headline figures) that financial and related professional services represent a large share of UK output and exports, including high GVA numbers and large tax contributions (with source attribution to ONS/TheCityUK etc.).

Implication: even if banks remain capital-strong, a structural relocation of activity can hit UK GDP through exports, wages, and tax receipts.

The risk channels

Channel 1 — Volatility, margin spirals, and liquidity demand

Mechanism: geopolitical shocks → repricing across rates/FX/credit → higher margins at CCPs → liquidity demand spikes → funding stress.

Why it matters for the UK:

• The UK intermediates a huge share of global rates risk, so margin/liquidity cycles propagate strongly through UK market infrastructure.

What to watch (practical indicators):

• CCP margin requirements and intraday calls

• repo haircuts and gilt-market functioning

• bid–ask spreads and implied volatility in rates/FX

Channel 2 — CCP concentration and “wrong-way risk” under sovereign pressure

Mechanism: fragmentation + recession + higher defence/industrial policy spending can raise sovereign-risk concerns; sovereign stress interacts with bank/CCP exposures through collateral valuation and funding.

Why it matters:

• The BoE’s CCP stress scenario explicitly includes sovereign-debt pressure alongside fragmentation and geopolitical tension.

• BoE Financial Stability Report highlights the same trio of risk drivers.

What to watch:

• sovereign spreads/term premia (UK and major peers)

• concentration of clearing members

• collateral quality mix and liquidity of posted collateral

Channel 3 — Regulatory and jurisdictional fragmentation (the “City structural risk”)

Mechanism: blocs require local clearing, local booking, local data residency, or restrict cross-border provision of financial services.

Why it matters:

• This does not require a crisis; it’s a policy architecture shift that permanently reduces UK cross-border financial exports.

• London’s dominance in OTC rates turnover makes it a natural target for “localise the plumbing” policies.

What to watch:

• equivalence/market-access decisions

• extraterritorial enforcement actions

• localisation rules for cloud/data and operational resilience regimes

Channel 4 — Sanctions, compliance, and secondary-sanctions spillovers

Mechanism: expanding sanctions regimes → banks de-risk counterparties/corridors → reduced correspondent banking and higher friction in payments/settlement.

Why it matters:

• The UK sits at the junction of US/EU compliance norms and global finance, so sanction spillovers disproportionately raise UK compliance and legal risk costs (even when the underlying exposures are offshore).

What to watch:

• sanctions list expansion and enforcement intensity

• compliance cost inflation and de-banking trends

• payment-corridor disruptions

(BoE highlights fragmentation of financial markets as a stability risk, which is the macro framing for this channel.)

Channel 5 — Cyber and operational disruption risk

Mechanism: geopolitical tension increases likelihood of cyberattacks and operational disruption—particularly on financial market infrastructure.

Why it matters:

• BoE Financial Stability Report explicitly links elevated geopolitical tensions with increased likelihood of cyberattacks/operational disruptions.

What to watch:

• FMI operational incidents, outages, ransom/cyber event frequency

• “concentration risk” in third-party/cloud providers

• cross-border recovery and resolution coordination

4) Putting it together: what each scenario implies for UK GDP + City risk

Scenario 1 (Hard New Cold War): highest GDP drag; highest structural City risk

• GDP: −3% to −8% vs baseline

• Key driver: policy-enforced fragmentation in tech, capital, and market access; potential “localise finance” logic

• Tail risk: crisis-driven liquidity spirals amplify the macro hit

Anchors: IMF fragmentation ranges and tail outcomes , BoE fragmentation risk framing , UK market centrality

Scenario 2 (Managed Rivalry): persistent headwinds; manageable but non-trivial

• GDP: baseline (0% vs itself)

• Key driver: compliance + selective controls; periodic volatility, not permanent separation

• Risk: episodic stress rather than structural deplatforming

Anchors: BoE FSR risk framing

Scenario 3 (Fragmented multipolarity): lower structural deplatforming risk; higher volatility drag

• GDP: −1% to −4% vs baseline

• Key driver: chronic uncertainty and repeated shocks; patchwork standards

• City: can sometimes profit from complexity/arbitrage, but volatility and localisation pressures still rise

Anchors: IMF fragmentation channels (trade/capital/tech diffusion)

5) A transparent “how to tighten the numbers further” (if you want publication-grade quant)

If you want the GDP ranges to be more formally parameterised, the next step is to pin:

1. UK sector exposure weights (goods vs services; finance share),

2. assumed fragmentation severity (IMF 0.3 / 2.3 / tail 7),

3. an explicit “City activity loss” assumption (e.g., X% decline in cross-border financial exports), using the City/ONS-derived sector output and export baselines.

Conclusion and Way Forward: UK Strategy in a Fragmenting World

Strategic Conclusion

The quantitative ranges presented earlier (−1% to −8% GDP level effects by 2035 depending on scenario) are not abstract modelling artefacts — they reflect identifiable transmission channels already recognised by institutions such as the International Monetary Fund and the Bank of England.

The evidence suggests:

1. A full New Cold War would be materially costly for the UK
   The UK’s exposure is amplified by:

   • Heavy reliance on cross-border services exports

   • Centrality in global derivatives and capital markets

   • Deep integration with both US and European systems

   • Material trade exposure to China-linked supply chains

   IMF research shows fragmentation losses ranging from modest (~0.3%) to severe (up to ~7% in tail cases) globally. Given the UK’s financial and services intensity, the upper tail cannot be dismissed.

2. The greater long-term risk is structural fragmentation of finance, not a one-off crisis
   A single market shock can be managed via liquidity and capital buffers.
   But regulatory ring-fencing, local clearing mandates, sanctions spillovers, and tech bifurcation could permanently erode UK comparative advantage.

3. Managed rivalry remains the highest-probability trajectory, but it is not benign
   Even under “de-risking not decoupling,” persistent compliance costs, duplicated tech stacks, and geopolitical risk premia will weigh on productivity and investment.

4. Fragmented multipolarity may be economically less severe than a hard bipolar split — but more volatile
   The UK could arbitrage between blocs, but at the cost of higher macro instability and regulatory complexity.

Strategic Way Forward for the United Kingdom

The policy response must assume persistent strategic competition, even if a full Cold War does not materialise.

Below is a structured framework.

1️⃣ Protect the Core: Financial System Resilience

Priority Actions

• Strengthen CCP liquidity backstops and margin transparency

• Maintain global clearing competitiveness while preserving regulatory trust

• Expand bilateral swap lines and liquidity coordination with major central banks

• Deepen cyber-resilience requirements for financial market infrastructure

The Bank of England has already integrated geopolitical fragmentation into stress testing — this must continue as a structural design assumption.

2️⃣ Avoid Strategic Over-Concentration

Trade and Industrial Policy

• Diversify critical inputs (rare earths, semiconductors, energy)

• Strengthen UK–EU technical alignment where commercially beneficial

• Expand CPTPP and Indo-Pacific trade engagement

• Build domestic resilience in critical technologies without full autarky

The goal is risk diversification, not economic nationalism.

3️⃣ Preserve London’s Role as a Neutral Financial Hub (Where Possible)

Under a fragmented world:

• The UK should position itself as the most trusted jurisdiction for cross-bloc capital intermediation.

• Maintain regulatory credibility and rule-of-law advantages.

• Avoid unnecessary politicisation of market plumbing.

If blocs fragment further, the competitive edge will go to the jurisdiction perceived as predictable, transparent, and operationally robust.

4️⃣ Invest in Productivity to Offset Fragmentation Drag

If GDP level losses of −1% to −8% are plausible by 2035, the only durable offset is higher productivity growth.

Key areas:

• AI integration into services exports

• Advanced manufacturing niches

• Clean energy and grid modernisation

• Defence-industrial innovation (leveraging AUKUS participation)

Fragmentation reduces global efficiency; domestic productivity gains must compensate.

5️⃣ Strategic Diplomacy: Middle-Power Coalition Building

The UK cannot control US–China rivalry.
But it can:

• Coordinate with middle powers (Canada, Japan, Australia, EU states)

• Support WTO reform while preparing for partial erosion

• Promote interoperability rather than exclusivity in tech standards

• Maintain dialogue channels with China even while aligning security with the US

This reduces the probability of Scenario 1 crystallising fully.

The Overarching Principle

Resilience over rigidity. Diversification over dependency. Stability over speed.

The UK’s structural advantage is flexibility:

• Not bound inside a single customs bloc

• Deep US security alignment

• Global financial centre

• Advanced services exporter

But flexibility only remains an advantage if managed deliberately.

Final Strategic Assessment

By 2035:

• The world will likely resemble competitive interdependence with hardened security alignment.

• The probability of a full New Cold War is real but not dominant.

• The UK’s main risk is structural erosion of financial and services primacy, not immediate systemic collapse.

If the UK:

• Strengthens financial resilience,

• Diversifies supply chains,

• Maintains regulatory credibility,

• Invests in productivity,

• And builds middle-power coalitions,

then even under fragmentation, GDP losses can be contained toward the lower end of the estimated range (−1% to −3%), rather than drifting toward the upper tail.