Last love letter by the poet still in private hands bought by the City of London corporation for display in museum

"Much have I travell'd in the realms of gold" wrote John Keats in 1816 – but a love letter the poet penned four years later has now fetched a record amount of the more earthly kind of gold.

The letter, written to his fiancee Frances Brawne, fetched £96,000 at auction.

Keats wrote the letter at his home in Hampstead, north London in 1820. It was bought by the City of London corporation, which manages his home as a museum, and will go on permanent display there.

The letter was the last of Keats's 30 love letters in existence still to be in private hands. The poet's love for Brawne, is bittersweet – although she loved him too, the pair were never able to make love because Keats had the highly contagious disease tuberculosis. He wrote in the letter: "I shall Kiss your name and mine where your Lips have been – Lips! Why should a poor prisoner as I am talk about such things.

"Thank God, though I hold them the dearest pleasures in the universe, I have a consolation independent of them in the certainty of your affectation."

A line – "you had better not come today" – that Keats has scrawled on the outside of the folded letter, appeared in Bright Star, the 2009 film directed by Jane Campion, which dramatised the love affair between Keats and his neighbour.

Less than a year after writing the letter, on 23 February 1821 Keats died in a small room close to the Spanish Steps in Rome. He was buried in the Protestant cemetery there.

Michael Welbank, chairman of the Keats House management committee at the City of London corporation, said: "We are absolutely delighted that our bid was successful. Keats is a hugely important part of our cultural landscape, and it is thrilling to know that we will now be able to display the letter where it was written.

"This letter, and the many other items on display at Keats House, will help visitors from home and abroad to gain an even deeper understanding of Keats's life, and the passions that drove him to produce such wonderful work."