Introducing a new local currency after an event

[Skvez]

(9 September 2011, 09:55)grumpy old man Wrote: All money is just a promissory note. The "bank of england promises to pay the bearer on demand the sum of"

But it's not. Before we changed to fiat currency the bank of England promised to turn your note into Gold, yes it was a promise but it was a promise backed by Gold. These days (since we changed to fiat) it's an empty promise.
A precious metal coin has intrinsic value, it's not just a promise.
Until there is an authority that we all trust (such as the bank of England (is supposed to be)) we need money that has intrinsic value. (Promissory notes only work if both parties trust the authority that issued it).

The problem with using precious metals for coins is that people faked them and filed pieces off them (the milled coin invented by Sir Isiac Newton was a breakthrough in anti coin-fraud) but all transactions have the risk that what you get is not all you thought it would be (the pig is sterile, the cow is dry etc, the bow doesn't shoot straight).