To view what's in the yard, you can also get the fast trains from Harrow and Wealdstone down to Euston. I think that they run every 30 minutes and they normally pass slow enough for most numbers to be obtained - you also get the view of Willesden Junction. BUT make sure you are on a Fast Service, the stopping trains drop down and pass under the fast lines and you cannot see anything on Wembley Yeard. However, you do get to see what (if anything) is in Stonebridge Park.

If you are looking to see what is in Wembley Yard, and dont want to fly past it on the main line, try taking the South Central Service Clapham Junction to Watford Junction OR Watford to Clapham.

It normally takes the underpass to cross to one side to the other at this location and therefore has to slow done to about 20 mph on this section of track

It is ideal for trying to get the 90's 92's 66's and 08's noramlly in the frieght yard.

This service is hourly Mon - Sat leaving Clapham at about 03 mins past and Watford at about 15 mins past