I *think* this curious question may be related to transport ...

Our local part of the South Circular had new streetlamps fitted by TfL
about a year ago. The lamp posts have two brackets (presumably for
hanging, say, "London Olympics" banners); the lamp housings are circular
and on the top of each is raised dome. I thought nothing of the latter
until, getting up early a few days ago, I looked out of our loft window
and saw that the domes are actually skyward-pointing bright blue lights
that were illuminated on this one occasion.

Does anyone know what these lamps are for? The South Circular through
Putney and East Sheen is pretty much exactly on one of the incoming
Heathrow flight-paths ... but surely they wouldn't be some kind of
landing lights, as we are about 9 miles away from Heathrow.

--
Paul Terry