Is this the reason why Mark Carney went Full "shock-and-awe"-tard this morning?

Households may have started to hoard their cash, with new figures showing that the amount of money being kept outside Britain's banking system is now rising at the fastest rate since the financial crisis.

As Sky News reports, in the weeks following the EU referendum, the rate at which households and businesses built up holdings of UK banknotes and coins rose above 8% a year for the first time since 2009, according to a Sky News analysis of Bank of England statistics.

The growth rate of cash in circulation has more than doubled since January, when it was running at 4% a year, with a sudden acceleration in the weeks following the EU poll.

In cash terms, the amount of notes and coins outside the banking system rose by £1.2bn since the end of May, and by £5.9bn in the past year - the biggest annual rise on record.

Sky News has also found that the proportion of UK banknotes circulating outside the banking system - in people's pockets, stored at home and outside the country - has now hit the highest level since 1979, as a percentage of GDP. 

Simon Ward, economist at Henderson Global Investors, said:

"People may be hoarding notes not for safety reasons but because the Bank of England is expected to cut interest rates significantly, possibly even imposing a negative rate on bank reserves, forcing banks to start charging for operating current accounts."

"Hoarding may also reflect increased demand for £50 notes due to uncertainty about their future supply,"

"(BOE) Governor Carney confirmed in June that there are no plans to introduce a plastic version of the £50 note, fuelling fears raised by Mr (BOE chief economist) Haldane's earlier speech that the Bank intends to restrict the future supply of cash in order to create scope for interest rates to fall further below zero."

The sharp increase in the amount of notes and coins outside the banking system is likely to sound an alarm for economists, some of whom have warned that with interest rates at record lows, there is diminishing incentive for consumers to leave their money in bank accounts, prompting them to hoard their money at home.