Actually we (i.e. UK) have been using decimal currency since 1849 - that is why the Florin or 2/- was introduced.
So we had the best of both worlds a decimal system and a duodecimal system. So we had 1, 1/2, 1/3, 1/4, 1/6, 1/8, 1/10, 1/12 and 1/20 of a pound.