Andy Dingley wrote:

Surely you've seen them ! 1960s(?) VHF coax connectors which I'm sure
the BBC must have used somewhere or other. They have a "tulip" shaped
connector with four leaves, two of which go inside and two outside. If
they won't mate, turn them by 90° and try again. The centre "pin" is
actually tubular, a miniature version of the shield.

That sounds like a description of a GR-874 (where GR == the General
Radio Company). Except you'd have to rotate by 180 deg., not 90. There
are later hermaphroditic coax connectors, GR-900 and APC-7, to name but
two. Pictures of all these at
http://ece-www.colorado.edu/~kuester/Coax/connchart.htm

Probably got the SWR of a hacksawed waterpipe, but they were workable
hermaphrodite plugs.

No, the GR-874 provided an accurate 50 ohm match up to microwave
frequencies. They're spec'd up to about 8 GHz, IIRC.

--
Andy