Tom - thanks. I am reassured. I'll try to get out over the next few days and observe the gauges.
Brent C - The switch sits between the water temp gauge and oil pressure. I thought (reasonably) that it switched between the two gauges not within the water temp gauge to show oil temp. I don't recall the CC mechanic telling me that the water temp gauge also showed oil temp when toggled, and the handbook, which is of more modern vintage than 1997, doesn't cover the point. So I will admit to being a numpty but I'm trying to learn! (No offence taken, by the way )
In Memoriam DMG