Police are offering a £10,000 reward after a female robber attacked the widow of the late film director Michael Winner in her own home before tying her up.
Geraldine Winner, 77, was beaten with an iron bar after the thief forced her way into her home in Knightsbridge, central London, late on October 9.
Her hands and feet were tied and she was blindfolded during the ordeal as the suspect stole jewellery and other valuables. She suffered serious head wounds and a broken finger in the attack.
Mrs Winner said she was extremely shaken: "They can take my possessions but they cannot take my memories."
Detective Chief Inspector Jane Corrigan, from Westminster CID, appealed for information and said the suspect was last seen walking up Kensington High Street.
She said: "I have never seen an attack of this nature committed by a lone female throughout my policing career."
Ms Corrigan added: "The suspect was very specific in terms of the items she was looking for and the motive is still being investigated."
Those items included a heart-shaped diamond pendant, cash including euros and a painting of St Mark's Basilica in Venice by the artist Franz Richard Unterberger.
Ms Corrigan said: "This incident has left Mrs Winner feeling vulnerable in her own home and I need the support of the public to solve this case.
"Someone knows this woman."
The suspect is described as a white woman, in her mid 30s, slim build, wearing a dark coat, dark trousers, dark floppy hat and carrying a large bag over her shoulder and a small rucksack on her back
Officers previously said a man and woman were involved in the burglary, however a Metropolitan Police spokesman said it has since been established that only one suspect was involved.
CCTV footage of the offender will be shown on the BBC Crimewatch programme on Monday.
Michael Winner, who made more than 30 films including the blockbuster Death Wish series, died aged 77 at his home in Kensington in January 2013. He had been nursed by his wife following a lengthy battle with liver disease.
After her husband's death, Mrs Winner, a former dancer who he married in 2011, said in a statement: "Michael was a wonderful man, brilliant, funny and generous. A light has gone out in my life."
During his career, the director reinvented himself as a restaurant critic, writing about food in his typically flamboyant style in his Winner's Dinners column for the Sunday Times.
His appearance in adverts for motor insurance coined the catchphrase "Calm down dear, it's a commercial".
He also founded and funded the Police Memorial Trust following the murder of WPc Yvonne Fletcher outside the Libyan embassy in London in 1984.