Determining the “relative” value today of a transaction in the past, is more complicated than it seems. There is no single "correct" measure, and as explained here, the answer depends on the context of the question.

This comparator gives you four types of contexts. They are a purchase of a consumer good or service, a compensation such as a wages or other types of earnings, an amount of wealth either financial or real property, and, finally, either a large construction project or historical event such as skyscraper or an earthquake.

Your query will generate answers associated with each of these contexts.

Note that prior to February 15, 1971 (“Decimal Day”), UK currency was expressed as pounds, shillings, and pence (£1 = 20s = 240d).