What was the shape of it? That's usually the first thing I try to nail down when people describe something like this. A lot of hovering lights turn out to have a rational explanation but the ones that linger in your head are usually the ones where the shape just doesn't match anything familiar.
I had something similar maybe six or seven years ago out near the edge of the New Forest, just sitting there above the treeline, no sound at all which is what got me. You'd expect a drone or a helicopter to make some kind of noise especially at night when everything else is quiet.
Did it move at any point or just stay in one spot? And roughly what time was this? I find the 2-4am window comes up again and again in these accounts and I've never quite worked out if thats coincidence or something else worth looking into.