(09 Nov 2015, 4:54 pm)buss14 wrote it was S891 ONL 4001
Can't of been 4001, as Tommy's photo was taken in June 2014 whereas 4001 will still in service at Darlington depot in November 2014: https://flic.kr/p/oZCe6y
Also 4001 had the registration S868 ONL, S891 ONL was 4005.