The change of the clocks to herald the end of British Summer Time turned in to a dark night for Barclays tech staff as routine maintenance in advance of the annual switch knocked over some of the bank's computer systems, preventing customers from accessing funds and using debit cards to make payments.
Barclays systems are now back up and running, but the breakdown in normal service proved a huge embarrassment for the bank as customers took to Twitter to vent their frustrations.
Barclays said the glitch materialised on Saturday before planned adjustments to coincide with the clocks going back.
On Sunday, Barclays said the problems had been fixed and the upgrade would be phased in, urging customers to use online banking services instead of calling because of the large volume of phone enquiries.