In the Coin Yearbook 2019 there is quite a good article about the decimalisation, a critique of the process which obviously is easier with benefit of hindsight. Don't have it to hand right now but I believe the article is of the opinion that having shillings & florins still around in 1990s was just a bit silly, and that the weight-to-value concept of coins should have been scrapped in 1971, allowing smaller & cheaper 5ps & 10ps from the off and therefore no use for 1s and 2s. Also would have meant the decimal halfpence could not have been so tiddly.