If you wish to read..

I don't think your question can be answered. A decent without being daft television now costs less than the average salary for a week, yet in the '70s it cost more than that. Yet the pounds cost, inflation adjusted tells you more about the subjectiveness of inflation calculation than it does anything else..

A decent car, full MOT, tidy and capable of A to B without breaking down costs what compared to a second hand pony & trap in the days of Johnson? In terms of percentage of income?

You answered your own question. Quantitive versus qualitative. Your question regarding a tenner for a departing nephew I suppose is in terms of that being an amount you can spend on what you need. If you win £100.00 on the lottery you are quite clear about what you will spend it on and your life goes on as before. Win £50,000,000 and that is life changing.