OMFG
Found it.
I found out it was the kitchen lighting at fault. I had my fluke on the switch when the lady walked up the stairs, I got 175v L to Earth then BANG ,,TRIPPED,,
I then isolated this feed to the kitchen light 2 way and tested again. Hmmmmmmmm No fault,No trip.
Sat with a bacon butty and tea for 3 long hours. Still no trip. So I reconnected the fitting feed back up yup I had voltage as she walked up the stairs.
After looking at the light fitting for faults I did notice some of the cieling had been re-skimmed !!!
I then pulled on the cable and this cable was running about 1mm under the skim to the wall up the wall then under the stairs.
Problem was J/b skimmed over in cieling loose connections. Then under the stairs it was passed under the carpet metal gripper. This gripper had cut into to the insulation.
So I then made safe and isolated the circuit.
5 hours later still no tripping going on.
Tests are fine and I think I solved the dam problem...
Thanks for all the help chaps I needed it.