Good morning to you, Alan.
Earlier than that for certain. They used to visit Sparkhill Park in the late 1940s. I saw them several times before I moved to Kings Heath in 1950 and as I've mentioned elsewhere, the tune that they were forever playing was the Andrews Sisters'
Money Is The Root Of All Evil. The record came out in either 1946 or 1947 according to internet sources.
They've now come into the 21st Century with a website here, but sadly it gives no historical information:-
https://www.bobwilsonfunfairs.co.uk/
It was incorporated as a limited company, Bob Wilson Funfairs Limited, with the following Directors in 1978:-
William Joseph Wilson - born February 1947
Mrs Emily Violeta Wilson (presumably his wife) - born January 1947
Robert Thomas Wilson (presumably William's brother) - born November 1958
None of these were appointed until 1991 and Robert resigned in March 2000, so presumably the business was started by their parents much earlier. The current address is given as Shipway Road, Birmingham B25.
Just in case the Moderators are getting a little tetchy, all this information is freely available on Google.
Maurice