UAV's, to the best of my knowledge, don't "go vertical" this way. Nice try, but.................no.
I suspect there are more types of UAVs than we know about. I've seen videos from several years back of small hovering devices that were capable of vertical maneuvering. I'm sure those sorts of machines have only gotten more sophisticated since then.
Also, if there were many helicopters and even fixed-wing aircraft in the vicinity of the objects in the London sighting (see maquiladora's post #15), it's clear that whatever was going on was a controlled test of some sort. Helicopters aren't used to chase UFOs, to my knowledge. Nor would a large fixed-wing aircraft be allowed to make a close fly-by of objects of unknown origin and intention that were being surveilled.
So your "no" is premature, I think...nor was I saying a definitive "yes", although I think the preponderance of the evidence supports the view that military testing is what is going on.
As for lights (speaking to your subsequent post), they are configurable in a variety of ways. Whatever lights were on the devices were likely there for some purpose involved with the testing.
Ever fly formation?
Welll, my relative worked around UFO craft that we had--that we'd been taught how to build by ET's . . . that were pilotless. Could go instantly to any spot on the globe under computer control--for recon or bomb delivery.
I suspect ET's have better models.