ATC High Altitude Frequencies
 

Hello!

Was just wondering if anyone knew (or if there are any ATC controllers for this region) some of the frequencies for high altitude aircraft passing over the Sheffield area. I'm talking flights like the BA flight from LHR to GLA while overhead Sheffield or some of the transatlantic flights out of London travelling up the UK. Was just curious - always fun to listen into! I find the London frequencies very easy to find, but the high altitude stuff especially in the north much more difficult to find.

Thank you:)