Last month hundreds of Westminster street signs were auctioned off. Their design with san-serif capital letters was the work of Sir Misha Black in 1967. One for Thirleby Road went for £240. It is not a famous street but my husband and I know people who live there, though they were not the lucky bidders.

I had never got a satisfactory answer from our friends about how the street is pronounced. They do not know. I find this odd. How do they get home by taxi? The crux is whether it is two syllables or three. By chance, a trip with my husband to North Yorkshire last week resolved the question. Four miles or so from Thirsk is the village of Thirlby (with no E). ‘Why should Thirleby Road in Westminster be named after a Yorkshire village and be spelt in a different way?’ asked my husband. ‘Good question for a change,’ I replied.

There is no other village in Britain called Thirlby. And the street is not exactly named after the one in Yorkshire, but after a man whose family took their name from it. This was Thomas Thirlby (1500-70), a local hero in Westminster, indeed the first and last bishop of Westminster. His bishopric was set up, with Westminster Abbey as its cathedral and Middlesex as its territory, in 1540. He lasted until 1550, when he was transferred to Norwich, and no successor was appointed.

Thirlby wasn’t fussy about his spelling. When he was commemorated by the street full of mansion flats in the 1890s, the spelling Thirleby was chosen. His family had moved south, his father being town clerk of Cambridge. In its name, Thirlby in Yorkshire shows Viking origins, –by coming from the Norse for a village or homestead. The thirl– element, meaning ‘serf’ or ‘slave’, is related to thrall. In Scots law the verb thirl meant to bind tenants to servitude at a mill, to grind corn.

Perhaps the vogue for undoing all connections with slavery should abolish the place-name Thirlby. Alf Wight, the vet who became better known as James Herriot, lived in Thirlby, so they might like to rename it Herriot. It would be good for tourism.