Police are hunting a woman who tried to throttle a one-year-old boy in a pram saying: “That baby would rather be dead.”

The stranger calmly walked up to the mother and child in a busy branch of Boots the chemist in central London before carrying out the attack.

Detectives say the child was only unharmed because of the bravery and quick thinking of the young mum who snatched her child away.

Police today issued CCTV footage of the incident which took place in a branch of Boots in The Strand at 12.30pm on January 16.

The footage shows the woman, described as in her sixties and wearing a distinctive striped poncho and deerstalker-style hat, walking the length of the store before approaching the mother and child.

She then reaches into the pushchair and takes hold of the one-year-old by the throat.

Police say the mother of the baby had originally thought that the suspect was going to just look and fuss over her child, but when she saw what was happening she immediately grabbed the suspect’s hand to pull her away.

The child was said to be have unhurt but left badly shaken and “traumatised” by the incident.

Today a worker at the store, said: “The mother had come in to get something for the baby because it was unwell and she was with the baby in the pram in the aisle.

“But this woman just walked up and started strangling the baby. She said something like ‘this baby would rather be dead’. You could actually see the pram move.

“Another woman nearby intervened to help get her off. The mother was really calm about it at first but then she broke down into tears because it was so terrible. She was distraught about it. Then the police came. “

The store manager, who did not want to be named, said: “The woman just came up from behind in the aisle and leant in.

“The security guard then came and asked what was going on and the woman said something like ‘that baby doesn’t deserve to be alive’. The security guard then kicked her out. She would not make any eye contact.”

A security guard, who had been following the woman inside the store, led her outside before she walked away toward Trafalgar Square.

Acting Detective Chief Inspector Dave Bolton, of the Westminster serious crime unit, said: “This is a highly unusual incident. The suspect who approached the family is a complete stranger to them so we are keeping a completely open mind about the motive.

“The mother was extremely fast in her reactions, she thought this lady was showing some loving interest but the next thing she knew she had her hand around her child’s throat.

“Our concern is that she might carry out this type of attack again but we have not had any other similar incidents reported to us. It is a stand alone attack but we are seeking to speak to this woman as soon as possible.”

Police tracked the woman on CCTV as she walked across Trafalgar Square but lost her as she mingled with a throng of protesters campaigning for Nigerian voting rights.

DCI Bolton added: “This woman was very distinctive and we are appealing to this group of protesters or anyone who recognises her to contact us.”

Scotland Yard has today released the footage in a bid to trace the woman, who is thought to have had a distinctive boil or a deformity on her eye.

She is described as white, in her early sixties, around 5ft 2ins with fair hair. She wore a white, red and grey poncho and was carrying a brown bag.

Anyone with information should call the police number 101 or contact Crimestoppers anonymously on 0800 555 111.