Tony,
You could well be right on that helo, probably getting confused but is that a S76? If it was would make sense as I think the QF is based at Northolt (?) Even so flying during the One Min Silence or flying directly over said Service whilst obviously sneeking a peek (bearing in mind the local police had stopped the local traffic in the area to preserve the silence....) is a bit naughty. And in reply to an earlier comment I dont think it was doing a "spy" job as I am sure the Sky Cops would be doing that job already or possibly the super secret Northolt-based Islander......