Northern Rock staff had barely drawn breath after the run on the bank before finding themselves facing a run of a different kind.

Savers, many of whom were queuing to withdraw their cash six months ago, could again be waiting — this time to put funds back in. The prospect of a flock back to Rock has been raised by financial advisers, who are telling customers with absolute confidence that there is no better home for their savings.

It’s a no-brainer. Rock’s best deals are a market-beating 6.20 per cent on a one-year fixed-rate Mini Cash Isa and 6.49 per cent for an online account for people over 50. Not only do these rates easily beat the next best in each category by at least 0.2 percentage points, they are 100 per cent guaranteed.

Even Rock savings accounts that do not offer top rates look good with a government guarantee attached. Rock’s no-notice Branch Saver, paying 5.5 per cent, is not so appealing beside 6.55 per cent on a West Bromwich Building Society Star Easy Access account, but add a government guarantee that you will not lose your savings and you have a package that rivals the best.

Given such apparent advantages, the uppity reaction to nationalisation from other banks — barely able to scrape together funding for a decent home loan, let alone pay out high interest – is understandable.

Ironically, Rock’s accounts also make rates offered by its closest rival savings institution - National Savings & Investments (NS&I) - look tame. NS&I, the only other government-backed savings body, offers only 5.1 per cent on its cash Isa and only 2.35 per cent on an Easy Access savings account. Such puny rates are a reminder that savers wanting security usually have to sacrifice rewards. They may also prompt an exodus of customers from NS&I to Rock.

However, NS&I’s deals may be a warning for new Rock savers that its rates may go the same way. Once Rock attains adequate funds, it will no longer need the extra business. The lack of interest in courting new customers is then likely to be reflected in lower rates. And if it is to get back into the mortgage market with better deals while proving that it has a safe business model, savings rates will have to be lowered to compensate.

Until Rock's great rates end, it is not so much a bank as a cash cow. Enjoy it while it lasts, but be ready to move on when the party is over.

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