A rare sketch of the poet Ted Hughes, drawn by his wife Sylvia Plath in 1957, is expected to fetch up to £20,000 when it is sold at auction in October.
Sketched in the first year of their tempestuous marriage, the drawing is her only known portrait of her husband.
The picture is one of more than 300 historical portraits belonging to the expert and collector Roy Davids.
Hughes burned many of his papers before his death in 1998 but gave the sketch to Mr Davids, a lifelong friend.
The portrait, taken from Plath's notebook, is on faintly lined paper and bears the inscription: "Portrait of me, made by Sylvia Plath, circa 1957, Ted Hughes."
Hughes and Plath met at Cambridge and were married in 1956. But their relationship was tested by his extramarital affairs and her history of mental illness.
Plath eventually committed suicide in 1963.
Compiled over 30 years, Mr Davids' extensive private collection contains almost 300 portraits of writers, artists, musicians and philosophers.
Other subjects include William Shakespeare, Charles Dickens, Lord Byron and the artist LS Lowry.
The collection has been described as "extraordinary" by Sir Roy Strong, former director of the National Portrait Gallery in London.
"Portraits have [always] had a magical fascination and that spell continues unbroken today," said Mr Davids.
The auction takes place at Bonhams' London branch on 3 October.