Superb find, Dean. It’s one of these:
IIRC, the cabs were sent to a coachbuilder on the South Coast, called Park Bank, or something. Unless this cab was done by the other one. My memory has more leaks than an LAD cab after the condensation from a couple of years’ being slept in has had its way with the floorpan. There is a full explanation on TNUK somewhere. There is also a very concise explanation on LKW Stefan forum.
This is the first time I’ve seen the interior. That engine cover looks nice and warm. 