Ed Sirett wrote:
I believe so. The correct fitting is 1/2" MaleIron to 15mm compression so
the flat end of the MI seals against the rubber washer. Compression
couplers or service isolators with the back-nut and olive removed also
work but you may find the end has a bit of damage which stop the seal.

Thanks, that makes sense - the correct solution would be to add a
section of copper pipe and one of these:

http://www.screwfix.com/app/sfd/cat/pro.jsp?id=18515


However, if the end of my service valves are free from dents, dings and
burrs such that I'd get a good seal the that should be OK.

Thanks.