Nice pic.

Re ejector seats it appears that the Mk GW 5 was fitted onto the Mk.6 and probably after the Mk.5 had been withdrawn from service around 1962. What I can confirm is that the Mk GW 5 seat was tested (on the ground) on a retired Sabre Mk.5 coded BB-261, a photo of which exists and I’ve seen in some publications. So one should study each photo to determine which seat is fitted.