The original steering wheel was far too big.
The solution:

Now this is nothing special, almost all Defenders in Germany are fitted with this steering wheel I guess.

I problem I faced was: It wasn't in the correct position when driving straight ahead.
But how to correct this and HOW TO DETACH THE THING?

All hints and clues were: "Put your legs below and use brutal force", "use a self made lifting block" etc.
They were all unsuccessful or simply too much work.
(But quite entertaining ;-) Like the "Three Men In A Boat" when trying to open a can)

My solution was a two-armed hub drawer every motorcyclist has.
A Euro-Coin put on the steering column, the hub drawer - OFF.
Aligned correctly, fixed again.