Proone
Colerne has UAS & AEF power traffic. Not a good mix with the Winch Launch Operation of 621. If it was Vigilant then just maybe..............
Lyneham is a non starter nowadays due to development, solar farms and other users.
For me it's Keevil I think as a co-lo with the GSA - although ACCGS has been trying to get onto Merryfield for years - originally as the preferred location when Weston-Super-Mare closed but I seem to remember the RN resisting due to the amount and type of traffic at Merryfield (Commando and Air Assault as well as training). That may have changed...............
Arc