The reason that only says 198, by the way, is because the people who installed our boiler last year were unaware that walls had any purpose other than to support whatever is screwed onto them.
However, recently we replaced the door from the kitchen to the utility room. The kitchen door used to be exterior (the utility room is an extension), and because of the fact that the house was nailed to its frame (rather than vice versa) it's probably fairly safe to assume it's an original fitting.
Today, my father-in-law took the hinges off the old door, just in case we ever need battered, rusting, overpainted, bent hinges for anything. Underneath, he found some cardboard that had been used for padding:
That's some kind of entry form for a competition that had a deadline of New Year's Eve, 1971.
It would appear that our house is 13 years older than I thought (but still not as old as me).