Many thanks, MicMac, skomaz & KenONeill for your quick and very helpful replies.
| have just bought the vehicle and am getting to know it. When I first drove it the rear wiper was in the 12 o'clock position and then something caused it to move to its normal resting place. However moving the washer stem forward does not cause the wiper to operate, neither is there the sound (if it is moved forward again (for the washer) of the washer motor. One thought was that it might be the relay, apparently number 377, situated behind a drop down panel in the driver's footwell. However, since neither the rear washer or wiper is working does that suggest an error at the switch. The previous owner, whose comments I trust, says that this has all been working fine so, if it is just the switch would a liberal application of a suitable spray electronic cleaner (even WD40) be a first step?
I notice that all of you are either in Scotland or the Shetland Isles which lends weight to my long held belief that these vehicles are generally fairly bullet proof.