The 18th century cartwheel pennies were even bigger, not so in circumference, but sheer weight. Nice mix of coins.
The ore decimal system is clear enough once you get used to it. 240 pence, thrupenny or 3 d, 6 pence, 12 pence to the shilling, 10 shillings, 2 shilling coin is a florin which was a 19th century decimal experiment, Crown which 5 shilling, half Crown which was 12 1/2 d and finally £1. There was also the Guinea which was £1 1s 0d which was mostly a unit for horseracing and other trades and still used for the horses. After decimalisation the shilling became 5p and the florin 10p, so the old Victorian experiment bore fruit. An MP introduced a bill in c 1870 for decimalisation. The government responded by introducing the 2 shilling or florin (10 to a £1) as a taster for decimalisation.