Hi, Dave, great selection of photo's again today. Now about that class 31 in green with yellow ends a one small double arrow. I thought that the livery seemed familiar, in that in an Ian Allan ABC for 1970, on page 37, there is a photo' of D5624 in exactly the same livery.
Good to see Little Bytham, a terrific ECML location for photography and railway history. Looking forward to more photo's.
All the best,
Market65.