The Boothroyd letters offer an insight into the friendship between the two women.
In one letter written in 1998, Boothroyd discussed a performance they both attended, writing: “I was thrilled!” before describing one of the actors as “a dear, dear boy”.
The then Speaker – a Labour MP from 1973 to 2000 – also mixed political life with personal observations.
In one letter, while discussing parliamentary events and social engagements, she joked: “When does a mistress become a spouse?”
Another referred to “the antics of that speaker woman paragliding over Paphos” after Boothroyd took up the sport on holiday in her sixties.
Later correspondence from 2014 mentioned being frisked by security services, royal engagements and problems with central heating.
Boothroyd, the first female speaker of the House of Commons, died in 2023, aged 93.