Those old enough to remember when payments to professionals were made in guineas (£1.1s or since 1971, £1.05) will be amused to read the list of lecturers and what they charged aquarists’ societies for an evening lecture.
You will see that the fees varied from 5 shillings (25p) to a guinea, with a number at half a guinea. L.G.Payne who has loomed large as a writer on reptiles and amphibians charged half a guinea plus travelling expenses.
In terms of pay today, I have used the data from Measuring Worth to see what one guinea was worth. Rather than using the Retail Prices Index, I have used the average wage as the comparator since pay has increased at a greater rate than prices. A wage of 1 guinea is approximately £150 in today’s money, and equates to 36% of average weekly pay. I have no idea what amateur societies, including the few aquarists’ societies that remain in existence, pay a visiting lecturer but if they have kept up with inflation, £75-150 would be the going rate.