The severe storms that swept across the UK late Friday caused a power failure at a HBOS data centre in Yorkshire that knocked out the high street bank's cash machines, branches and online banking services.
The disruption to services hit customers at 8am on Saturday morning as they attempted to make banking transactions at the start of one of the busiest weekends in the pre-Christmas shopping calendar.
The bank's entire ATM network went down and customers also found their cards being rejected at the cash machines of other banks and in some shops. Harried shoppers were allowed to withdraw cash up to a maximum of £200 only at the counter, where bank staff were forced to record transaction details using pen and paper.
Power was only restored to the centre via a back-up generator late Saturday morning and normal service restored on the high street by 14.30. Online banking remained offline until 18.30.