On reflection I think he might be he who became Chief Plod. It may have been him - certainly was a Chief Plod - who told me of his unique piece of uniform.
When Plod officers used to have APM (Assistant Provost Marshal) on their armbands, Chief Plod had PM on his. As I was was told: "Not even a 4* has a badge all to himself"
But now they are all RAFP, probably including the Chief Plod.
O tempora, o mores .....
Edited because I can't type - thanks Jcak!