DETECTIVES are appealing for a witness, who may hold clues to the murder of Wanstead pensioner Ursula Caddock, to come forward.

A woman is reported to have handed Mrs Caddock's son's benefit book in to the post office in Wanstead Pharmacy on the same day that the 82-year-old was brutally mugged in her street, Halstead Road.

Mrs Caddock, known as Joan, was pushed to the ground by the thug at around 11.30am on Thursday, April 8, fracturing her left shoulder and hip. She died as a result of her injuries almost three weeks later.

Her attacker, who returned for her bus pass as she lay stricken on the pavement, made off with her handbag containing £100 cash her son's benefit money which she had just collected from the post office.

Later the same day the book belonging to her son Derek, who lived with his mother, was handed in to the Wanstead High Street pharmacy's in-house post office.

Heading the murder investigation, Detective Chief Inspector Bryan Sweeting said: "The same day Joan was robbed, her son's benefit book was handed into the Wanstead Pharmacy post office by a lady of about 70 years who was wearing glasses and had grey hair.

"She was doing a public duty and probably didn't associate it with the murder.

"She's not been back to the post office since but may return on Thursday (today) as benefits are often paid once a fortnight. We would appeal for her to get in touch to help with our enquiries."

The mugger could be linked to a series of other muggings which occurred in the area around the time Mrs Caddock was attacked.

Urging caution while the man is still at large, DCI Sweeting said: "While we do not wish to be alarmist in any way, I would ask people, especially women, to be alert and aware when withdrawing money from a post office or bank.

"Look around you before you withdraw any cash and when leaving. If you see anything suspicious report it to police."

This week her devastated son John, 61, of Buckhurst Hill, spoke of his grief at losing his loving mother.

Mr Caddock said: "I couldn't speak for a day after she died it was the shock. The sooner they catch this person, the better.

"People have been so supportive to all of us. We've been inundated with cards from neighbours and friends. We've since had about five visits from the police and I cannot praise them enough."

Praising his mother, he said: "She used to come up and visit us every day to cook dinner. She didn't have to but she wanted to be involved, she was devoted to her family."

Mrs Caddock was born of a family of eight children in Islington and lived in north London for most of her life. She spent a few weeks in the Land Army during the war and Mr Caddock has memories of being carried in her arms to the air-raid shelters.

Her husband Jack, known as John, served with the Army in Egypt during the war. He died of cancer 30 years ago.

Any witnesses, especially the woman who returned Mr Caddock's pension book, should ring DCI Bryan Sweeting at the incident room on 8345 3865 or Crimestoppers on 0800 555 111.