I located in Italy a Jag xjr v8 - year 1999 - and wish to buy it from the present private
Owner.
While testing the car I noticed that the gearbox lever cannot be moved from P position unless pushing several times the brake pedal.
Can anybody give his advise about this fact? tks

 

There is a brake switch (located in the well, fitted next to the brake pedal assembly) and a solenoid (located in the gear shift housing).
Both of them can be at fault.
If the contact is on, and you push the brake pedal, you should hear a click at the gear shifter, which is the solenoid releasing the shifter to move.
There could be several reasons if one of the 2 is not working properly.
Do the brake lights come on?

 

+1 Eric. Almost certainly the brake switch.