The other side of that though is that there is something thoroughly depressing about spending the whole of a warm sunny day inside out of the sun. We value our warm sunny days so much the last thing we want to do is spend them out of the sun, and through the busy tourism months sunny days really aren't that rare.
I remember Sega World (or whatever it was called) at the trocadero in London, it was always dead when it was warm, and was often quiet outside of tourism peak summer months, and that's in the middle of Londonn.
You run the risk of building something people dont want when they are there, and would want when they aren't there. Both leave you with a limited customer base.
On the flip side of that; dependant on what’s on offer, could it potentially pull people during a typical tourism off-season when outdoor attractions are either closed or possibly not as desirable to visit?
Also, this attraction is likely to rely less on tourism “seasons” than the Trocadero Centre, as even though the Trocadero is in the centre of London, that might actually work to its disadvantage, as based on all of the other major London attractions, it likely had very limited accessibility by car. I’m not sure of the exact specifics of Joypolis at the Trocadero, but based on most attractions in London, I’m guessing that there was very little car access. As such, it likely had to rely a lot more on inner-city tourism to London than it might have done had it been built outside of London and had easier car access.
Joypolis also looked quite small in comparison to your regular indoor theme park, which might not have helped in terms of pulling people there.
If people can get there by car with reasonable ease, then I think it could perhaps generate a busy crowd during the colder months, or on rainy days.
The aforementioned example of the Nick Universe parks in America, as well as other places like Galaxyland in Canada, seem relatively successful, so I think a substantial indoor theme park could work in Britain.
