Looks like 94438, MK1 ex- Travelling Post Office vehicle
TOPS retains some history of the previous movements of 94438, including its final TPO working to Low Fell and back (see below).
The year each working took place is not shown (only the day and month), but I assume the movements as far as Harwich took place in 2003.
5E53 Euston Downside Carriage Shed - Willesden PRDC 14/10/03
1E53 Willesden PRDC - Low Fell 14/10/03
5E53 Low Fell - Tyne Yard 15/10/03
5M91 Tyne Yard - Low Fell 15/10/03
1M91 Low Fell - Willesden PRDC 15/10/03
5M91 Willesden PRDC - Euston Downside Carriage Shed 15/10/03
5Z92 Euston Downside Carriage Shed - Wembley Yard 07/11/03
6L33 Wembley Yard - Harwich Parkeston Yard 08/11/03
5Z80 Harwich Parkeston Yard - York 27/04/??
6Z83 York Yard North - Toton Up sidings 11/10/??
Current location Toton TMD
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94438 is seen in a TPO set at Carlisle in June 2003:
https://www.flickr.com/photos/85304690@N05/22203148963/ (Photo: loco+)
Painted blue for internal use at Toton, seen in 2008:
https://www.flickr.com/photos/37260/46578923265/ (Photo: 37260)