The message
from Malcolm contains these words:

I don't know of any law which prohibits the capture and release of
Rabbits or Brown Rats. Perhaps it was never thought necessary as no-one
would be daft enough to want to do it :-))

In the case of rabbits, I think landowners have been known to
trade/capture/release ones infected with myxymatosis and that other
deadly rabbit disease whose name has just eluded me.

Janet.