OK. I’ve checked the number of stations I believe to have been open in 1968 (pre-Victoria Line opening) and I make it 272, not 273 as I first thought. This includes two for Edgware Road, two for Hammersmith, two for Paddington and two for Shepherds Bush as I believe was and still is the custom (especially as Shepherds Bush (Hammersmith & City) has changed its name). Don’t know why I had 273 in mind. The number currently open is 270. This is by my reckoning and confirmed by other sources such as Wiki. I have checked the list contained in the Wiki article against mine and it is identical. To get from 272 in 1968 to 270 today I think the following must be taken into consideration:
I'd say it's more than just "custom" to count two Shepherd Bush stations - they really are very separate, at some distance from one another; even more, perhaps, than the two Edgware Road ones. I don't think anyone has
ever considered the two SBs to be one station! And I've always thought Hammersmith a bit borderline to be treated as two, but I guess you do have to go out and cross the road. But Paddington really puzzles me; although historically the different bits of the underground there had separate origins, they're all part of one interconnected complex (albeit via the mainline concourse for some connections), and the distances surely aren't much worse than some of the Jubilee Line "connections" of recent years... (If it's counted as two, then is it the Bakerloo plus District/Circle as one, and the H&C/Circle as the other?)
By the way - in terms of 272 or 273, did you count Ealing Broadway as two? LT have, I believe, always counted that as two, with the Central being deemed part of the mainline station, and the District being "separate".