I replaced it only four years ago with one of these:
A neighbour once told me that this hard water area plays havoc with ball valves as even a little piece of grit or limescale can lodge in the valve and cause it to fail. Is this true?
Can I unscrew the large blue cap (see Screwfix product picture above) and clean out the innards? (I have an isolating valve on the water inlet.) Or is another replacement needed? Sure, it's only a fiver or thereabouts, but do these things need replacing every FOUR years?