I hate

...the inconsiderate fcks sitting in the tube train, looks up at my pregnant wife and not offer her a seat. fck em. two mornings in a row now.

i would have asked one of them nicely and loud enough to offer her the seat.

Yep shame the carriage into it. Yell out "Who is going to be the gentleman whom will let by pregnant wife sit down?" If no one gets up then you can go into a torrent of abuse about how they must all be worthless pieces of shit. That's what I would do, but I don't mind making a scene.