Britain’s economy is shrinking at its fastest rate since the 2008-09 financial crisis, making a Bank of England rate cut today “a foregone conclusion”, the publishers of a closely watched business survey said.

Financial data company Markit said the full version of its monthly Purchasing Managers’ Index (PMI) yesterday showed a sharp hit to business activity from June’s European Union vote, just as a one-off preliminary PMI did two weeks ago.

Chris Williamson, Markit’s chief economist, said the numbers pointed to Britain’s economy shrinking by 0.4 per cent in the three months to September, a rate not seen since early 2009 when the BoE last cut interest rates.

“The unprecedented month-on-month drop in the all-sector index has undoubtedly increased the chances of the UK sliding into at least a mild recession,” he said.

Economists polled by Reuters last month saw a 60 per cent chance of recession in the wake of June 23’s vote to leave the EU, and Britain’s National Institute of Economic and Social Research (NIESR) gave only slightly longer odds when it cut its growth forecast earlier yesterday. NIESR has said it does not expect the slowdown to match that seen during the global financial crisis – Britain’s worst recession since at least the 1930s – and Markit said there was “substantial uncertainty about the extent of any downturn”.

Almost all economists expect the BoE to reduce rates by at least a quarter percentage point to 0.25 per cent today, but they are more split as to whether it will restart its quantitative easing programme of government bond purchases.

“A quarter-point cut in interest rates therefore seems to be a foregone conclusion ... though the extent and nature of other non-standard stimulus measures remains a far greater source of uncertainty,” Williamson said.

Measures to tempt banks to lend at record-low rates, as well as possible purchases of private-sector assets such as corporate bonds, are potentially on the table alongside buying more government debt with freshly created central bank money.

Other business surveys have also shown large drops in confidence, though not always on this scale. Consumer confidence has fallen sharply since the referendum, but measures of retail spending have yet to show much of a hit.