Probably depends where you are in the country. I think the reduction of industry and practical fields of work has a lot to do with it. Appears to be better supported in the north where you still have a larger industrial base.
Lots of other factors too. Practical skills no longer taught in schools, modelmaking gets a bad PR from the popular press, increases in rules and regulations. Some folk in this hobby don't help either, I have come across certain individuals so condescending and downright misanthropic, they make me wonder why they bother to join anything that's supposed to be sociable.
I got my interest in modelmaking from my Dad. I have uncles who did a bit of modelmaking and tried to encourage cousins, but none of them continued with it.
I'm North London based, for model boaters, there are a couple of ponds close by- Broomfield park, and Highgate pond. You occasionally see a bit of activity at these places, but it's a bit erratic, and in the case of Broomfield, the water is now poorly maintained by Enfield's local authority. Highgate is a screaming nightmare to park, being a well heeled area it's residents only parking and double yellows everywhere.
I was a member of North London Society of Model Engineers for many years, and they have a nice if small, boating pond at their site in Colney Heath. However it's primarily railway focused with marine always a bit poorly supported, and they stopped formal meetings over a decade ago. I believe a few modellers meet up for a sail on weekdays, not much good unless you're retired.
