Barclays, Santander, Nationwide and NatWest customers have been urged to take £1 out of their bank account as we head towards Christmas.

The best savings account where an overlooked bank pays 8 per cent "guaranteed interest" has been revealed – and you can open it with £1.

Analysis by Shawbrook Bank indicates that 1.4million savers with fixed deals ending before January could face financial setbacks if they do not switch accounts promptly.

Adam Thrower, the Bank's head of savings, warns that failing to act quickly "could be costly" for these savers.

However, Rachel Springhall, finance expert at MoneyFactsCompare.co.uk, said: "The cut to interest rates is not all doom and gloom as savers can easily switch their flexible pots elsewhere. Challenger banks are offering attractive returns and it would be unwise to overlook them when they have the same protections in place as a high street bank.

"Savers need to proactively keep on top of the best rates and review their pots regularly to see if they are getting a raw deal."

Principality Building Society's Six Month Regular Saver offers an impressive 8% interest on savings, with a minimum deposit requirement of just £1 per month.

The rate is fixed for 6 months until the bond matures (when the account comes to an end). The estimated balance would be after 6 months based on depositing £200 every calendar month, an eye-watering £1,227.53.

Recommended reading:

Nationwide: Customers offered £20,000 interest free loans

Nationwide Building Society will offer bigger 0% loans for green retrofitting

Nationwide adverts banned by watchdog as branches closed

This is based on you paying £200 a month for 6 months and making the first payment on the date the account was opened.

This calculation is for guidance only, to show you what a future balance could look like. It does not consider your circumstances.

The building society says: "Our 6 Month Regular Saver is designed to help you save on a regular basis over six months. You don't have to pay in money every month."