Used the Alinco handheld and 40cm whip. Not as bad for overload from all the masts as I thought it would be, even on 145MHz any interference was gone at the lowest attenuator setting (about 3dB?) so it wasn't really a problem.
Most of the transmitters on Billinge are between 163 and 183 MHz, so some way from the 2m amateur band, and on the mast furthest from the summit. Apart from Airwave TETRA around 393MHz, I don't think there are any UHF transmitters up there any more.
I made 8 QSOs from Billinge Hill, 7 on 145MHz and one on 433MHz. The furthest was G4ING who was in Hyde, around 42km away, also only on a handheld.
Summit of Billinge Hill
View towards Winter Hill
Remains of something
4 masts on Billinge Hill
Cropped from my phone camera so not the best quality, this is the one with the broadcast antennas on, and looks like it would have had emergency services pre-Airwave. About halfway up are the DAB yagis pointing towards Liverpool. Wish FM 102.4 looks like 2 crossed yagis, one towards Wigan and the other towards St Helens. The other mast is probably from the analogue mobile phone days.
Very busy mast with most of the high VHF stuff on. Furthest from the summit.
Apart from the microwave dishes, only a couple of low VHF dipoles. These might not even be used any more.
On the way here, I stopped at the slightly lower Ashurst Beacon, further north on the other side of the M58. This would be a much better place to play radio from if not after the SOTA activation, with a large car park and land open to the public. There are two viewpoints with car parks, about 2km apart on the ridge, one is better for the north, the other for the south.
Here is the trigpoint at the south viewpoint (168 metres)