I was curious about why my friend thought this was a Spitfire control grip and in trying to find when it was used, I can see the general type was used on de Havilland Vampires and Venoms and on Gloster Meteor as identified by Wurger. However, the buttons at the tip of the control grip for the de Havilland applications are different to my own which I have learned are identical to those fitted to later Gloster Meteor Night Fighters. The C-Button is for CAMERA; the M-Button is for MUTE (VHF).
The Pilot's Notes for Meteor Mk 4 shows a very Spitfire-esque cord-bound, circular handle that may have created confusion somewhere along the line.
The Pilot's Notes for the Meteor Mks 11 to 14 Night Fighters show a handle identical to my own complete with C and M Buttons, Gun Safety Switch and Brake Lever.
So a final thank you for your knowledge that has resolved this little conundrum.