Non screw TRV

[CH1975]

Hi guys. Help needed
Some of the TRV’s in the house have been replaced as they were showing signs of age etc. most were the screw variety so no issues. However 2 are like a bayonet fitting (non screw) and I’m trying to replace them without replacing the whole valve.
Any help is much appreciated
Pictures attached

 

[muggles]

Wow they look older than I am! Never come across any replacements to fit that kind of attachment I'm afraid, likely to need new valves. If anybody can help, however, I'd suggest it would be https://www.heatingcontrolsonline.co.uk/replacement-trv-heads-c-28_51.html