Isn't Jane from the same area as Jeremy? And lived there in 1985.
Perhaps she could enlighten us to what gym Jeremy may have been on about.
Strange as it may seem to Adam, there were methods of communication prior to the internet. One such being Yellow Pages which we know JB was familiar with.
Other than keep fit classes, mainly held in village halls, there wasn't the availability, of gyms in 1985, as there is now. Maldon would have been the nearest place which may have had a purpose-built gym, but to get there by bike would have taken several hours and the necessity of negotiating the infamous Market Hill, after which an inexperienced cyclist would have been fit for nothing. More convenient would have been a bus which passed the top of Head Street and took half an hour.