Actually I may have answered above question myself. At a Mog gathering yesterday I noted a year 2000 T16 engined Plus 4 had the same Lucas STC4016 wiper stalk with relay operated intermittent wipe. Unless anyone can claim otherwise it seems possible this was used on same model at least back until 1992 when M16 engine in Plus 4 was replaced by T16. Not sure of wiper arrangements on other Morgans of this era though
