[hairyhandedfool]

I'm going to take it for granted that you want buildings that still exist as opposed to just used to be there.

there is a station building just off the midland mainline, (fast line side) south of luton airport parkway near a tiny village that I believe is called east hyde. the station was Chiltern Green.

there are also remnents of two stations between west hampstead thameslink and kentish town but they are little more than bricks and stuff in the ten foot now.

also heard that some of the stations on the old luton to leighton buzzard line still exist, can't confirm it though.