This came as 2787 but the numberplate appears to say 2767 to me, but I found a ref in an SLS journal saying 2767 was ‘open cab’, however there are many such observations in the journal at Swindon Works that are definitely incorrect. It is fitted with a Collett bunker. There is a a picture of 2787 in Locos Illustrated 118 p. 27, where it is shown with pannier tanks, and overall cab and an original bunker (not Collett extended). It suggests that the picture was possibly taken when it had the pannier tanks fitted in 1918. It is in works grey and has riveted tanks. Your photo shows a loco in the later condition with the Collett bunker extension and a new smokebox. 2767 was fitted with pannier tanks in July 1921 and also would have had riveted tanks, too, at this date. I am guessing that it retained its open back cab. However, later in its career this loco could have had a Collett cab and bunker fitted as well as a new smoke box front. It would also then be as in the photo.