London Underground: Blair, Cameron and Johnson on Tube
Prime ministers have been keen to be seen mixing with other passengers, while London mayors have praised the London Underground network which opened 150 years ago.
But do MPs really mind the gap and squeeze into those carriages along with the rest of the capital's commuters and travellers?
Adam Fleming spoke to Conservative Mark Field, Labour's David Lammy and Liberal Democrat Simon Hughes to test their knowledge.
Some images are from Pathe News.