":Jerry:" gurgled happily, sounding much like
they were saying:

Here's a picture.

http://www.trevor-turner.co.uk/pages/Caliper_Small.html

Definitely designed for being wound in with the appropriate tool.

OK, so you can get a G-clamp onto the piston.

But not on the P6 Rover...

shakes fist at SteveH
That's the last time I believe him...

It's just down to "Will the clamp turn it rather than push it?" (Very
unlikely ime of turny-piston calipers) and "Is there anything solid
enough on t'other side...?"

...the calliper is mounted, via a rather involved mounting/pivot bolt,
to the diff carrier casting and even if one was to unship the calliper
from the car, were one normally has a casting there is nothing more than
a tin cover protecting part of the internal handbrake mechanism.

Partial parts diagram here
http://www.anugraha.org.uk/rover/par...r_cal_ipb2.gif, shows the
cover and some of the internal components.

Ah, the good ol' British Motor Industry... Why make something simple...?