Just as another data point I can hear GB3MCB up here in IO83LR at sea level.
It is peaking to s3 this morning and quite audible.
I make it's freq 1296.846325MHz - GPS locked IC-9100 and using Spectran to measure audio tone.
See attached file.
Using a 16 ele at about 30 feet AGL /ASL
As for 6 mtrs - MCB also seems a little off freq there as well, not sure why as my IC-7800 is also GPS locked, maybe they use a master reference ?
73 Tim G4WIM / KT6UK