Yes, TFL manage it as effectively a store for big items. Museum money, if money there is, comes from the main show in Covent Garden. I did have a look at visitor figures from Bord Failte. A fair comparison of how much interest there is in railways might be to take two sites which are geographically contiguous. One railway related, one not. So here goes: two attractions a 4 minutes walk apart.
Donegal Castle 63072
Donegal Railway Heritage Centre 7000
Now we can cavil over stats but that’s got to be interesting….the Donegal museum is a very slick and attractive operation but even that struggles.
Most attractive thing in the country is apparently Phoenix Park visitor centre with 1.9m recorded.
I also had a look at the UK. Biggest heritage railway is NYMR which pulls in about 350,000 punters a year. Even so, that makes it rank about 150th on list of top UK attractions.