Been at this for about 25 years now and the ones that stick with you are always the low, slow movers over treelines. Not the zipping across the sky stuff. That detail alone puts it in a more interesting category for me.
What was the light situation? Solid colour, pulsing, multiple points? And roughly how long did you watch it before it moved off or disappeared? Those two things will help narrow it down a fair bit.
Warwickshire here so I know what aircraft and helicopters look and sound like at night - they're everywhere round here with Birmingham nearby. If there was no sound at all that's the bit worth focusing on. Most people underestimate how much noise even a fairly distant helicopter makes.
Post back with more detail, plenty of people here will have thoughts.
