From the article:
"At 11AM, the British government announced they would increase interest rates 200 basis points, from 10% to 12%. ... [later that day] an interest rate increase of another 300 basis points, from 12% to 15%."
That means millions of ordinary people suddenly, not even overnight but on the same day, found themselves paying 5% more on large loans such as mortgages. To make completely clear, that had a very significant negative impact on a very large number of ordinary people.
Also from the article:
"The cost to British taxpayers was estimated at roughly £3.3 billion."
That's an average of over £128 per tax payer (3,300,000,000 / 25,700,000 tax payers in 1991-92 according to [0]). Again, to clarify, tax payers are not some "egos at the Bank of England", but ordinary people like me and you.
Or to summarise in simpler terms, a small number of the very rich got significantly richer by making a large number of ordinary people significantly poorer.
EDIT: Corrected figures. Thanks @philipkglass for spotting.
[0] https://assets.publishing.service.gov.uk/government/uploads/...