Rovex Coupling
Triang Couplings
The first Triang couplings were the Mk2(a) which had a plain drop arm, the later Triang coupling, the Mk2b had the "skid" on the drop arm, apparently to add weight and give more positivity to the hook. The familiar tension lock Mk3 was introduced in 1957 with, I believe, the TT system and then transferred to OO.
The loco tender has a hook coupling, while the coaches have Mk2b couplings. It looks like someone has found a box with a loco and tender and has added a couple of later coaches to make the lot a bit more attractive!
The lack of track is probably because the original "Universal" track is incompatible with the later "Standard" track and including Standard track would certainly stick out like a sore thumb!
Rovex Universal track
Triang Standard track