Footage of a flickering orb hovering over the Thames Estuary has sparked excitement among UFO watchers.

The clip was filmed by a motorist driving through London in the night and posted on YouTube on February 6 under the user name Space999dude.

He wrote underneath the entry: “I took this from my car but had to go because of where I was parked. Seems too bright for a boat and looked like it was above water.”

He added: “It was a very long way off and I was at full 40x zoom hence the shaky footage.

“I always carry a camcorder in my car as saw something a few years ago and think more people should be looking and keeping cameras at the ready.”

The 53-second clip has attracted nearly 8,000 views and hundreds of comments.

Some question the veracity of the clip, suggesting it shows lights from a ship, distorted by a thermal air layer, and others claim it is a downright hoax.

But another pointed out: “It could be anything...that's the nature of UFO sightings...Keep looking and filming!”