As internet and mobile banking have taken off, branch use has plummeted, prompting banks to try to make access to their expensive high street sites more convenient.
Lenders have already been lengthening Saturday hours and even opening on Sundays.
More than 100 branches will be open on Monday, with RBS and NatWest opening 34, Barclays welcoming customers to around 50, and all of Metro Bank’s 34 stores available.
The RBS and NatWest branches will focus on face to face services such as mortgage advice – particularly as such meetings take time, which customers cannot take in the middle of a working day.
By contrast, most transactions have moved online, and the bank holiday means the payments systems will still be closed over the long weekend.
Around 200 of the bank’s staff will be in branches on Monday, in a major departure for the lender – it has never done this in the 144-year history of bank holidays.
The public holidays were so named because MPs wanted to make sure businesses did close. By making banks shut their doors, they forced other firms to close too.
But marketing experts do not expect the name or the expectation of a holiday to change just because banks are increasingly open anyway.
“If it wasn’t called a bank holiday, then it might not work – there is a certain institutional ring about it, giving the whole country a guilt-free day off work,” said Jon Forsyth, founder of communications agency Adam and Eve. “It is very British really. It is no longer about banks, it is just an excuse for a holiday.”