I guess it's because of regressing to the past, which happens such a lot. Both my mother and my FIL lost all sight of current monetary value.
And a few weeks ago I was in my mother's care home when some of the ladies were having their nails done. I stopped and said to one of them what a pretty colour varnish it was, and picked up the bottle to have a look. 'Yes,' she said, 'and do you know, it was only one and six!' .
(Twelve and a half P for those who didn't grow up with old money!)
I think 1/6p translates to 7 and a half pence in todays money. An even better bargain for a bottle of nail varnish. My last bottle cost me just over £10. Next time you see her ask where she gets her varnish from and do they do a nice coral colour