Just come back from Turweston to our farm strip which meant an overflight of Cranfield. Called 5 minutes out and told them I was at 1,700 feet to maintain VMC and would like an overhead transit with FIS. The lady on ATC came back with "Report the M1" then "Report Overhead" and finally "Report leaving the frequency". She was busy with other transits and circuit traffic but it was all very straightforward and I felt it was very professional. What I think I'm saying is that if you make clear your intentions, Cranfield ATC have always been very helpful in my experience.