Hi, I have checked it with fiat scan, at first the car was doing what it should but there was a fault with the pump logged so I cleared that and was fine untill it was hot when it started to play up.
The pressure is as you said 50 bar, at idle and in neutral it took about 5 minutes to fall from 50 to 40 bar before the pump came on and went straight back to 50, going through the gears it did drop a bit quicker but shot straight back to 50 when it got to about 41 bar.
We took it for a drive and it was fine for a while with the pressure showing between 41 and 50 then when in neutral it wouldnt select 1st and the pressure had dropped to 36 bar but not falling too quickly.
When the engine was switched off and back on the pressure was back up to 50 and all was working ok.
I am thinking it is the pump or relay, he is going to order a relay on monday and failing that there are sets of brushes for sale so was hoping to try a set of these first as the pumps arnt cheap.
Luckily this car isnt his every day drive so there is no rush to fix it, car is an 04 with only 40k miles and has been stood for quite a while.