An OAP uses a cashpoint – many of the machines are vanishing from the high street (Image: Matt Cardy/Getty)
And more than 250 free-to-use ATMs are also closing every month amid changes in the way the UK's cash machine network is funded.
Meanwhile, over the year, 102 so-called "protected" machines closed in more remote areas which receive boosted subsidies aimed at keeping them open.
The closures mirror the decline in the number of bank branches with more than 3,300 in the UK closing since 2015.
Campaigners say this is leaving communities, many of them rural, struggling to access the cash they rely on.
Jan Shortt, the general secretary of the National Pensioners Convention, said: "The financial sector is in danger of isolating millions of older customers with its constant closure of high street bank and building society branches, coupled with the removal of many cash machines.
"This is going to leave many pensioners needing to draw out larger amounts of cash each time because it will be less convenient to manage their affairs whenever they choose - and this, in turn, could leave them vulnerable.
"Just because we can do something doesn't mean we necessarily should. Everyone needs to be catered for and it's completely unacceptable for millions of older customers to effectively be told to 'take it or leave it'.
"The financial sector needs to adapt to the customer, not the other way round."
The Which? report calls on the Government to appoint a regulator to protect access to cash.
It says more than 25 million people across the country still need access to cash despite the increased popularity of digital and card payments which are vulnerable to IT failures.
Analysis has found that leading banks suffer at least one major security or IT glitch a week, causing chaos for customers.
Jenni Allen, the managing director of Which? Money, said: "We have serious concerns that the alarming rate of ATM and bank branch closures risks leaving people facing an uphill battle to access the cash they rely on.
"Cash is also a vital back-up as fallible digital payments grow in popularity, so the Government must appoint a regulator to oversee these changes and ensure no one is excluded and left struggling to go about their daily lives."
Some parts of the country are making the move away from cash more quickly than others.
Withdrawals in London and the South-east fell by 8.5 percent and 7.7 percent respectively in 2017/18, but the rate of change elsewhere has been more gradual.
Northern Ireland saw a drop of just 2.1 percent, while the Northwest, Scotland and Wales were on 3.3 percent.
No joy for locals in Oxfordshire (Image: Daily Express)
Mike Cherry, of the Federation of Small Businesses, said: "The rapid pace of bank branch and ATM closures is hurting small businesses all over the UK.
"Millions of small firms have customers who want to pay using notes and coins. The vast majority of shoppers either use cash frequently or want to see access to it maintained."
Mr Cherry said that bank branches and ATMs were a "natural draw" for high streets, giving shoppers a reason to visit, "meaning increased footfall and greater sales at surrounding businesses as a result".
And he warned: "When bank branches and ATMs are lost, local growth often takes a hit.
"It's time for a regulator to be given explicit responsibility for protecting access to notes and coins, otherwise we risk drifting into a cashless environment that we're simply not ready for yet."
Three-quarters, 73 percent, of the