Problems with low water pressure up at the house (well actually, it was more that there was low flow - flow and pressure were good for a few seconds then flow drops off) and as it's rather close to Christmas, can't get a plumber (as expected).
So did a wee interweb trawl and discovered that the first gizmo in the pipework was actually a
filter. What's more it has a tap on top that you turn off, then unscrew the filter from the bottom, clean, screw back on, turn tap on. Easy. Turns out there was a pile of thin strips of plastic and stuff gunking up the wee stainless filter, cleared that and bingo! Back to normal ;-)
Cheaper and much more satisfying than getting the pros in!!