What aircraft has a single constant orange light?
From your description it sounds more like the International Space Station than an aircraft. That looks like a small orange or yellow light because it's the reflection of the sunlight For that reason you're most likely to see it in the hour or two after sunset, and it's clearly visible with the naked eye in good visibility. It's much higher than aircraft and takes about 90 seconds to travel horizon to horizon. Obviously you won't hear it or see anything on aircraft tracking sites.

That said, ymb1 suggested looking at this ISS tracker site. Assuming your 2120 was in British Summer Time (UTC+1), the ISS would have been somewhere over the South Pacific Ocean at that time, which would rule it out.