If the words police were on it it is not a camera van.
All that I have ever known had cameras inside the van pointed out the window usually side window, they then record everything they see, and it runs on a continuous loop type setting, it will only keep a image when the operator presses the save button, most are digital, a few older ones are still vhs cassette!!
They wouldn't have taken any notice of you at that speed.
To dispel the myth, there is NO such thing as an official allowance, each force has thier own criteria for "allowance", most are 10% +2 on a+b class road unless dual carriageway, where they range between 10% + 3mph to 10% + 7mph.
Stop worrying, the SECRET FOUR LETTERS will get you out of any points and conviction anyway, should the worst happen, but whatever you do if you receive a NIP, notice of intended prosecution DON'T ANSWER IT UNDER ANY CIRCUMSTANCES, only with 1 of the secret 4.
tabetha