I don't happen to have the usual samples in front of me for comparison but it looks like a bit of a hybrid with a UKmade barrel/barrel nut and certainly the or parts of the backsight assembly. I bet ZGB and BP will have some pertinent comments to add.
Certainly most of the well used/thrashed trials guns were converted to DP and used at Hythe in order to teach the unit military training cadres about the 'new' Bren they were soon to be issued with and teach. At Warminster we had an attendance register relating to these Courses which also included the new BOYS rifle and 2" mortar. There is an interesting photo (clearly posed......) shows the instructional cadre teaching soldiers the new Bren prior to shooting it. It shows the Rifle Brigade Depot at Winchester at the rear of the recently demolished camp 25 yard range.
Interesting.