Jan Larsen wrote:

I tried to turn the square bit, nothing, then turned the collar thing
underneath the square bit, got a bit of a dribble but not much, after a
few more turns I noticed water emerging from underneath the collar and
in fear of water emerging at considerable speed in directions other than
my original intention and the swift administration of the mother of all
bollockings by the wife I decided it best to turn the collar the other
way and ask first.

You're doing it right; there's nothing particularly complicated about
it. Presumably yours is jammed internally or something. You certainly
shouldn't need to undo the knurled collar.

David