Or, to put it on other terms: if £30 then = £4,000 now, then £10 then = about £1,300 now. It seems that £10 was a perfectly reasonable tip for a departing nephew to expect from an aunt then. But no such would expect £1,300 now.

So -- is there a different sort of measure that will have to be applied to smallish amounts? If so, what?, and how is it to be calculated?