Thames Water collapse could trigger Truss-style borrowing crisis, Whitehall officials fear

Senior Whitehall officials fear Thames Water’s financial collapse could trigger a rise in government borrowing costs not seen since the chaos of the Liz Truss mini-budget, the Guardian can reveal.

Her chancellor Kwasi Kwarteng’s promise of £45bn of unfunded tax cuts, the sacking of the most senior civil servant at the Treasury and Truss’s refusal to have her sums checked by the independent Office for Budget Responsibility spooked investors and sent the value of UK debt instruments, known as gilts, plummeting.

While Kwarteng’s successor, Jeremy Hunt, reversed the tax plans and stabilised debt markets, the UK’s cost of borrowing has crept up again in recent months amid geopolitical shocks, including the Middle East conflict.

The UK’s £2.7tn of debt stands at about 98% of GDP, and will continue to swell as the government needs to borrow heavily to overhaul its ageing network of pipes, cables, water and power infrastructure.

Whitehall officials expect any restructuring that involves investors losing money in Thames’ water operating company to trigger legal action against the government and Ofwat.

Still, officials view a swift renationalisation that forces lenders to bear losses as preferable to a long, drawn out debate over the fate of Thames that weighs on the UK’s needs to raise capital for infrastructure projects and for its general debt issuance.