Ex-RHD actually 8) It turns out they were both behind the driver's glove box. The indicator relay is hidden pretty much out of sight behind some gaffa tape and wires so had to find it going by ear. Was expecting a round one, by mistake, but it's just a smaller version of the hazard one. So, replaced for a correct unit, now stable and plink-plonking as it should. Only niggle now is that both dash arrows light up, dimly; not the sided one only when indicators are on. Is this a common aspect of irregular wiring? My other cars didn't have this 'feature'.
There's nuff gaffa tape under the dash in general, and I'll also have to tackle a dead rear screen heater and a dormant pos. 2 on the interior lights switch. Door courtesy switches are all fine.