The one sure thing about Northern Rock is that its shares are not worth 163p, last night's closing price after yet another day heading south.

They are worth either considerably more or considerably less.

The point was made by William's de Broe's Jim Wood-Smith, clarifying a recommendation to "hold" them in his lively weekly newsletter. After all, the Rock's book value is supposed to be 380p.

True, no bidder is rushing to pay a premium over that – but it still leaves room for a brutal discount to leave a profit on 163p. So the City is convinced that if a bid was coming it would have come already.

Yet even if the Rock just runs down its outstanding mortgage book quietly, 300p is a realistic number – providing that the world's banks start lending sensibly to each other again, sooner rather than later.

It is a big providing.

The timing is critical for the Rock. If it has to go on paying the Bank of England seven per cent on its #3 billion for months on end there won't be much left.

Even that supposes that the Government refrains from declaring the Rock nationalised in disgrace, and its 146,000 shareholders a bunch of "whingeing grannies" like Railtrack's.

It is what the Bank calls a "downside risk".

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 Since the queues outside the Rock's branches melted away at the sound of Chancellor Alistair Darling's blanket guarantee – ostensibly covering every penny in every bank, though we have not had the detail of that yet – it has been supposed that any threat of contagion damaging the credibility of the wider banking system has melted, too.

Well, that is not the verdict of a poll by YouGov published this morning.

This found that a daunting 46 per cent of the British say they no longer regard the high street banks as trustworthy, rising to 48 per cent for building societies.

So much for mutuality.

Bizarrely, only a quarter are unhappy with online banks, or say they no longer trust supermarkets to provide financial products.

That is only slightly more than the 23 per cent who told the pollsters they don't trust any financial institution at all.

In other words, one in five of our fellow citizens would rather deposit their money with a supermarket acting in partnership with a bank, or over the internet with a bank's cyber-offshoot, than direct with the bank itself.

Stranger still, only seven per cent distrust "investment companies" and six per cent "loan companies". This was not the findings from a rather dodgy opinion poll either.

YouGov knows its business and questioned 2,485 people, more than enough to be considered a statistically reliable sample.

We must conclude that little more than half the population sleeps at night with money in the bank, or sleeps more easily with an overdraft than with an account in credit.

So where do they keep their money?

National Savings & Investments says it has had a terrific September, the Post Office, too.

Yet if this poll is half right, there are billions sitting in the banks waiting to be withdrawn at the faintest whiff of trouble.