The BBC quoted the London firm as saying the previously unpublished, 43-page document is part of the "world's finest collection of Dylan Thomas inscribed books, letters and manuscripts" to be put up for sale.

The price tag for the entire literary treasure trove is about $500,000, the British broadcaster said.

"It's an impassioned account of her love for the dead poet and reflections on her new role as a literary widow," Rick Gekoski told the BBC of Caitlin Thomas' writings. "It is an exciting new addition to our knowledge of the relationship between Dylan Thomas and his wife."

Gekoski added that the journal predates her 1957 memoir, "Leftover Life to Kill."

"It is very raw and emotional. Sometimes she says, 'Oh, my God, I wish I'd never married him' and at other times she wishes she was in the grave with him giving him a cuddle," Gekoski said.

Dylan Thomas died in 1953 at the age of 39. Caitlin Thomas died in 1994 at the age of 80.