The thermostat housing also houses the oil cooler inside the same alloy unit. I would check that the seals on the oil pipes leading to it are intact to start with.
It PASSED!!! Happy days! Just a couple of advisory points, the main one being the rear fuel pipes are badly corroded, i'm sure Rimmer Bros do these so no problem there, but I also got a "Low Ride Height", it is on lowered spax springs (30mm) but i've never had that before with other cars i've lowered.Good luck for the MOT starchild