Well, that explains why my central heating system (combi) has been randomly losing pressure. Found this while I was doing 10,000 other jobs on the weekend... :-(
Any ideas what to do with this? I'll give most things a blast but this makes me slightly nervous - I've got visions of the coupling snapping off if I touch it. How much do you reckon a plumber would charge to fix this? I'd reckon at least 2-3 hours work. Another pic from a distance:-