In this story, Michael says he telephoned the Victoria and Albert Museum. This would be the usual way for a person living in London to get the sort of information he wanted.
Michael also mentions a promising little company called ICC. Imperial Chemical Industries is now a large international company, but Michael imagines that in 1851 the occupants of the house might have left him shares in that company which would, a hundred years later, be worth a fortune.
The rates of pay for the workman in 1851 are listed as 5/- (five shillings) a day and 2/6d (two shillings and sixpence) a day, which is equivalent to 25p and 1.5 p in the decimal currency of today.
Michael still lives in the house where he found the "curious thing" and now one almost expects him to discover other fascinating objects.