Welcome back Nigel, are you the same guy who also used to have a series I LS400 and came to the Doncaster meet?
It is the engine coolant radiator they are refering to, there is a transmission intercooler mounted at the bottom, a leak occurs allowing the 2 fluids to mix and wrecking the gearbox.
Suprised to hear an air strut is "misting" I thought there was no fluid in them to produce a mist being an air suspension unit.