Must find one magazine where is shown whole history of this machine, I think that on very start it was pale blue!
That's right No.1 some PR.XIs were PRU Blue all over. However, PR.XIs in India had Medium Sea Grey uppersurfaces with PRU Blue undersides.
The USAAF also flow the PR.IX and they have two colour profiles, one was bare metal with red panels under the engine exhaust and red on the rudder. The others carried the normal PRU Blue. Both these types were flown with the 14th Photo Squadrom of the 7th Photo Group which was based at RAF Mount Farm, Dec 1944