[exim] Find version

Lord am I thick!

You would think spending an hour googling the various 'exim display
version', 'exim show version' and 'exim --version' may have given me a
hint how to find the version of exim on the system - but no, it teases
me but won't tell me.

I've tried exim --version but it complains:

/usr/exim/bin/exim --version
exim abandoned: unknown, malformed, or incomplete option --version

Would someone put me out of my misery (by telling me how, rather than a
shot in the arm :-))

Thank you