Having a cigarette in a layby and could hear a rather loud humming noise such as a jet. we hear this quite a lot as there is a naval base nearby, however this object was emitting much more light then a standard jet and wasn't moving as a jet would. it seemed like a grey boomerang shape with a white light and moved towards lands end direction before disappearing. the sky was very clear andi cold many stars with ease so visibility shouldn't have been an issue. as the area got quieter i could hear the craft more vividly and it seemed like a different noise to a jet, it seemed less like a fuel engine noise. i recorded a video with a shakey hand, but you can see the quick change in direction and blinking lights rather clearly. the object suddenly disappeared into the night a few seconds after emitting a larger scale of light from itself. a helicopter following the same sort of path went passed around 4 minutes later, this has the usual red blinking light and nothing else.