Post-Brexit currency slump gives banks a £6bn boost

The value at the half-year point was £87.2bn, up some £6bn, and the biggest quarterly increase since the global financial crash of 2008.

The value of third-party deposits, a key indicator of the health of the banking sector, rose by an almost unprecedented 11.2% to £43.5bn, the highest value since June 2013.

'This is almost entirely down to the exchange rate and the depreciation of sterling after the Brexit vote,' said Jeremy Quick, director of the banking and insurance supervision and policy division at the Guernsey Financial Services Commission.

The value of sterling against the dollar had fallen 15 cents by 30 June, when the figures were collated, after the Brexit vote on 23 June.

Mr Quick said that a lot of third-party deposits – which do not include inter-bank deposits – were not held in sterling but were often in dollars.