Glad to.

The question relates to a radical idea of light put forward by a group known as POAMS. I put forward a counter argument that involved the possibility of being able to measure the time of flight of a single photon in vacuum, a notion that I considered would question their basic stance. They insisted that such a measurement (even an approximate one) involving just one photon would be impossible to achieve because of the uncertainty principle. At the time I was unsure about this and I could find no information regarding any such measurement as having taken place, so I could not follow my argument through.

In the wake of the "amplitude of a photon" thread I thought it would be an opportune time to ask the question here, and the answer given is much what I though should be the case, although I had the uncertainty concept a little confused.

So, to answer your question, I am not simply talking about measuring the speed of light, I am specifically questioning what we can and cannot know regarding the time of flight of a single photon in vacuum between a source and sink. And given Ken's answer, I am now armed to resurrect my original argument with POAMS.