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.
much more recent
knock walls down
dig floors up
do goodness knows what
do the things I didn't understand
exquisite copper plate writing
contained my impatience
a treasure map
nailed to a beam
the Victoria and Albert Museum
soaked in a special solution