Interestingly, this photo has always been described as being of ex-P&M 1152 - even by ColourRail who sell copies of it (they have been informed of the error!). 1152 had a completely open cab rear!
The 7 Swansea Peckett Es were a very varied bunch - no two were the same and their idiosyncracies enable them to be identified accurately even when the numberplate is obscured. The giveaway here is the rear coupling. 1151 has the same 2-long-link rear coupling - the only loco to do so.
Edit: see this taken on the same day.
Cheers
Dave