Here are two old coins (one is just about 100 years old) that my father obtained when he was in charge of the payroll at Ever Ready, Park Lane, Wolverhampton, in the second half of the 1960s. These coins were still legal tender, and in use, at the time. They were still legal tender until decimalisation in 1971.
On the left the outline of George III is just discernible on this well-worn coin and must have been minted before his death in 1820, so it is probably over 200 years old. The George V ‘thrupenny’ bit is remarkably clear given that it had been in circulation for about 50 years (though it has lived in a small box for the last 50 or so).
On the left the detail of the George III coin is completely worn away, but it was still worth six pennies. I wonder how many Christmas puddings it was used in.
So what would these coins be worth at the time? In 1820 six pence would be the equivalent of £1.90 today, in terms of buying power, and the three penny coin would be worth 60 pence. (Calculated using Measuring Worth).