Has the TV show made at the old school gone to air?

I lived in the Watford area from 1949 until I joined the RAF in 1955 and went to secondary school at Hunton Bridge. During a recent visit the first to England since I moved to NZ in 1967 I managed to return to the old school and was interested to see it was closed. A team from the BBC arrived when I was there and was preparing the building to shoot a pilot TV show. I wonder if that show has gone to air, I believe it was a detective show set in the 1920's and starring Nigel Nigel Havers.