April 5: The immediacy and urgency of Dylan Thomas’s passion for his wife Caitlin are revealed in a series of lyrical love letters by the poet which are to be auctioned next week.

The Welshman wrote the letters shortly after he was introduced to Caitlin in a London pub by the artist Augustus John in 1936.

They show Thomas was besotted by the young dancer and incapable of living without her. The depth of feeling that fuelled one of the most turbulent literary romances of the 20th century is clear.

The earliest surviving love letter from Thomas to Caitlin, which is expected to fetch up to £3,300 at Sotheby’s in New York on April 13, was written when she was recovering from an illness in hospital.

“Tell me everything; when you’ll be out again, where you’ll be at Christmas and that you think of me and love me,” wrote Thomas, who married Caitlin the following year.

“I don’t want you for a day (though I’d sell my toes to see you now my dear, only for a minute, to kiss you once and make a funny face at you): a day is the length of a gnat’s life: I want you for the lifetime of a big, mad animal, like an elephant.

“You’ll never, I’ll never let you, grow wise, and I’ll never, you shall never let me, grow wise and we’ll always be young and unwise together... I love you so much, I’ll never be able to tell you; I’m frightened to tell you.”

In another letter, which should fetch up to £4,100, Thomas admits “I lost you in the morning”, thought to be a reference to one of the many quarrels which the couple had in a tempestuous relationship which lasted until his death.

He continues: “I don’t want to write words, words, words to you; I must see you and hear you; it’s hell writing to you now... you are really my flesh and blood Caitlin whom I love more than anyone has loved anyone else. It’s nonsense me living without you, you without me: the world is very unbalanced unless in the very centre of it we stand together all the time in a hairy, golden, more-or-less unintelligible haze of daftness.”

Thomas was already spending a good deal of his time in an alcoholic haze and it was drink that eventually killed him at 39 during a visit to New York in 1953.

The couple’s 17-year relationship was strained by lack of money, his drinking and unreliability and by the affairs which both of them had. Yet, somehow, they stayed together.

This resilience is summed up in the copy of the first edition of Thomas’s first book 18 Poems which he gave to Caitlin and which is also in the Sotheby’s sale estimated at £19,000 to £28,000.

Inside is an inscription stained by an unidentified liquid which could be water, beer or tears. It reads: “From Dylan to Caitlin. Lovingly — in spite.”

In 1975, Caitlin sold the letters and the book to Maurice Neville, an American whose collection of modern litera- ture is being auctioned by Sotheby’s.

Caitlin spent the latter part of her life in Italy but, when she died in 1994, her body was brought back to Wales and she was buried alongside Thomas in the Carmarthenshire village of Laugharne, where they had lived for most of their marriage.