Thank you to everyone for the advice ..... some good news this morning .... (for me .. not for GB ..

Alko specifications : Tow ball height = 350-420mm (ground to ball centre)
The beast, empty/uncoupled = ground to ball centre = 375mm
so looks within spec, we'll just have to see what happens when I hitch the thing up and load it. I'm hoping to be able to do that this weekend sometime but have other commitments to deal with first.
So GB, you'lll have to wait for a decision before you
dream decide to mod yours !!

@mikedundee
If the springs are red, which you can easily spot looking into the wheel arch then it is lowered by 20mm and are irmscher springs.
The rear springs looked pretty new, black with a yellow vertical hand painted line on them, one of the shockers has an irmscher label on it, too dirty to read right now. The lines for the self adjusting air are present, cable tied out of the way.
Front ones I don't remember much about, it'll need to go back up in the air to check !!
Does this help any ??