Actually, the introduction of the florin, in the 1800's, worth one tenth of a pound (or 2 shillings) was supposed to have been the first step in decimalisation! The Guinea was a foreign gold coin, and slightly larger than the sovereign, so it was worth more.
Don't forget that Europe has previously had a common currency (In the Roman era), and that didn't last.
As for the Euro, it may be easier for tourism, but it appears we will lose much more in other ways than we gain in convenience. My vote is NO