The rededication of the revamped burial plot of Harriet Smyth, who was born in the town of Niagara Falls, has taken place at Kensal Green Cemetery, in Harrow Road, Kensal Green.

The ceremony took place on Thursday, July 11, led by members of The Friends of Kensal Green Cemetery.

The project was triggered by the detective work of Declan Walton, of Steeple Ashton, near Trowbridge, Wiltshire, who told the Observer: “I’m a long retired UN official, but I have been interested most of my life in the French poet Stéphane Mallarmé.

“Through that interest I found out more about Harriet Smyth, who became close friends with burgeoning poet Mallarmé when they both were on holiday in Passy, then an affluent suburb of Paris, in the late 1850s.

“Mallarmé, who was 17, was very fond of Harriet, who was actually four years older than him but hid her real age from him.

“It wasn’t what you would call a romantic attachment – he was in love with her cousin Emily Sullivan – but it was a close friendship.

“She was very beautiful, talented and of angelic character, but was dying of tuberculosis and finally died in July 1859, by which time she had known Mallarmé for probably a couple of years.”

Harriet, who at that time was living in West Kensington with her family, including her English father, was buried four days later in the same grave as her aunt’s father James Aungle, which accounts for the two sets of initials – ‘HS’ and ‘JA’ – and dates inscribed on the grave’s footstone.

Grieving Mallarmé, already anguished by the death less than two years before of his younger sister in similar circumstances, wrote two poems about Harriet in French, whose English titles translate as ‘Her Grave Is Dug’ and ‘Her Tomb Is Closed’, but never published them.

He did, however, copy them into a notebook with a footnote dedication that is held in the collection of a Paris library, the document that helped stoke Mr Walton’s intrigue.

Mr Walton said: “Harriet’s life and death inspired Mallarmé to produce these two poems in or about the month of July 1859, although they are not great examples of his work.

“The poems are very early exercises and are not representative of his more mature style. This one unremarkable grave has been the subject of two poems by a major European poet.”

Mr Walton added: “The interesting thing about the whole affair is that Mallarmé is thought of as a very quintessentially French poet, but he spent time in England, had his close friend buried at Kensal Green Cemetery, later became an English teacher, which he wasn’t very good at at all, and he published in English review books and gave lectures in Oxford and Cambridge later in life.

“Perhaps his interest in English was first sparked by his friendship with the two girls, Harriet and Emily.”

When Mr Walton and his wife tracked down Harriet Smyth’s grave a year ago, he found it overgrown and lacking a tombstone.

The ledger, the flat stone laying down on top of the grave, was cracked and the inscription had been worn away by the elements to the extent it was illegible, but there was a footstone that had been later added by the cemetery which helped identify what the couple were looking at.

During last week’s rededication ceremony, Mr Walton placed a new tablet at the head of the burial plot that, for the first time, explains Harriet’s relationship with and influence on her French friend.

“Neither the cemetery staff nor The Friends of Kensal Green Cemetery had the foggiest idea of the connection, nobody knew at all,” said Mr Walton.

He wrote about Harriet Smyth, of whom no photograph nor illustration has survived, in an article contributed to a new book published in France last month called Études Stéphane Mallarmé.

The editor of the article, the retired Professor Gordon Millan, sent a well wishing message that was read out at the rededication ceremony.