Thanks for the help everyone Im going tomorrow so I will have a look.

Well I went and would you believe it the heavens opened so I never quite made it to the footbridge at South Kenton. Am I right in assuming that you see the same trains on the station as you do at the footbridge or is there another line you can see from the bridge.
I found the footbridge at Willesden no problem and you do have a good view but it was tipping it down so didnt stay long.