My late mum did on a local council one once - she was a lifelong Tory voter but finally really disliked Boris - hell would freeze before she ever voted Labour and she thought Lib Dem were pointless. She liked the thought of improving the environment so chose Green.
I felt a little bad I may have influenced her as in often mentioning the failings of the Tories, without my Dad there to share their ongoing joint insistence Tory was the only sensible choice ever. Also bad that she was fairly unaware of the rest of their policies, but whilst mainly competent digging deep into policy discussion wouldn’t have really gone anywhere.
So I can imagine some older voters could go from Tory to Green very easily, if they are just considering on a basic level with decades of views on each parties informing them. Not enough to really alter much though. It’s a ‘nicer’ switch than Tory to Reform really and appeals to those who have care for the environment.
Just to add - I have actively posted in a Tory vote for her as well as the outlying Green one.