Ok, so "we" have an issue with the AC/alternator belt tensioner.
The belt is still "on", but the tensioner pulley (the plastic part) has separated from the metal centre. Probably never been replaced. The spindle has stuck to the bolt.
It's proving difficult to remove and it looks like the way forward is to remove the AC pump (system already degassed ages ago).
Can somebody please confirm that undoing just these two nuts (+ancillary pipework) are all that's needed to take it off?