My elderly mother (94) has arthritis in her hands, and has a bit of trouble using the taps on kitchen sink (which is some 55 years old). I planned to fit some quarter-turn tap revivers with lever handles to make things easier for her, but the tap threads are not standard AFAICT. The thread on the valve unit is bigger than 1/2" BSP, but smaller than 3/4" BSP. Measuring it up as best I can, I reckon it's
24mm OD with a 1.5mm pitch. From tables on the net, it would appear to be a metric thread, M24/1.5.
Pictures her: The taps
Changing the whole tap is not an option. Bearing in mind the age of the taps, and that the connections are probably corroded and seized solid, and that they're in an awkward place up behind the sink, I wouldn't attempt it myself (even though in my own house, I probably would), and my mother doesn't want the upheaval of having a plumber in to do it. She'd rather put up what is not a major inconvenience for her.
First question: is it likely that it's a metric thread? Were some tap valve threads from the 1960's metric?
Second question: are metric-thread quarter-turn tap revivers available in the UK? If so, please give the link, as I can't find any.
Third question: if no revivers available, is it possible to get some sort of sleeve adaptor, M24mm thread outside, 1/2" BSP thread inside, that would then take a standard 1/2" tap reviver? What is the correct name for such an adapter? Would fitting such an adapter actually work, or would it prevent the seal on the reviver from making contact with the valve seating in the tap?