The M&S Premium Current Account, which is now available after a two month pre-registration phase, costs £15 a month, or £20 with insurance. In addition to basic banking features, holders also get a range of M&S-related perks and vouchers.

Meanwhile, the retailer has confirmed that it will open 12 more in-store branches by the end of the year - in locations including Oxford, Norwich and Lisburn - taking the total to 28. By the end of next year it plans to have 50 branches.

M&S is pitching itself as a credible, alternative choice for UK banking services, extending its trusted brand into a sector beset by a succession of defaults, mis-selling scandals and rows over rich bonus pay-outs.

Branches are open seven days a week with the same hours as the stores that they are housed in - far longer than most high street rivals. In addition, a new pager service has been introduced so customers can continue to shop or visit the M&S café, rather than wait for an appointment.

Current account customers also have access to 24x7 UK call centres and online banking - complete with a virtual assistant named Hanna - although the Web site suffered some teething issues yesterday morning, according to This is Money.

Colin Kersley, CEO, M&S Bank, says: "We understand that our customers want to bank at a time that suits them and our branches are open the same hours as M&S stores, including weekends. We've been opening branches across the UK over the summer and it's been great to see such a high level of interest."

Other retailers, including Tesco, Asda and Sainsbury's have also been flexing their corporate muscle to take advantage of public dissatisfaction with traditional banks while brand new players such as Metro and Virgin are trying to get in on the act as well.

A recent poll from uSwitch found that 80% of Brits would consider moving to a non-traditional banking provider, with firms like John Lewis scoring high on issues such as trust and customer service.