TV programme about the PRU

About 10 years ago, a programme was shown on TV about the Photographic Reconnaissance Unit during the Second World War, and I am trying to find out the title so that I can set about obtaining a copy. One of the participants in the programme was the father of a friend of mine (Ronnie Knight), who was a navigator on Mosquitos in the PRU. Sadly he died a couple of Christmases ago, leaving all sorts of memorabilia, including a drawer full of recon photos!
He was stationed at RAF Benson (I think!), and was awarded the Belgian Croix de Guerre and the Belgian Legion d’Honneur.
Any help about the name of the programme, or the PRU in general would be greatly appreciated.
Cheers.