Just spotted a GWR Class 387 unit pass Watford operating a 5Z service from Bletchley T&R.S.M.D. to Selhurst T&R.S.M.D. - I'm struggling to understand why this move would occur? What's a GWR unit doing down there? I know they occasionally test them to Brighton, but this is based from Wembley EFOC... Any ideas?
Wembley is a normal staging point on the test running, has been since they started with the first 387/1s. AC runs are often from Bletchley to Crewe via a reversal at Wembley in both directions, so a round trip often uses four separate Train IDs.
Visits to Selhurst are also not unusual during the test phase. It may just be that it has a specific item of test equipment and suitable Bombardier outbased staff, and that Bombardier have maintained the same access arrangement as they had for the earlier members of the class.
I doubt there is anything especially significant about the move. They don't just 'occasionally' test them to Brighton, they all do the same DC mileage as a proportion of the overall testing mileage.
Here's today's moves, showing the normal sort of pattern:
http://www.realtimetrains.co.uk/search/advanced/XBQ/2017/05/30/0600-2000?stp=WVS&show=all&order=wtt
What you saw appears to be an
STP Bletchley to Selhurst via Wembley EFOC. Not unusual AFAICS.