A family told today of their horror as their two-year-old son was grabbed from their shopping trolley.

Maria Gunn, a 20-year-old care home assistant, was shopping with her partner at Asda in Brighton Marina on Tuesday when a woman lifted little James from their trolley.

Maria ordered the woman to return her child but she refused, saying: "He's not yours, he's mine."

The mother, terrified the woman was about to run off with her son, pinched the woman's arm and wrestled her son back.

Supermarket staff intervened and police were called.

Police said later the woman, known as the Black Widow, was a well-known eccentric and was "harmless".

But Maria was still shaking from the ordeal today: "What happened to poor Holly and Jessica in Soham immediately flashed through my mind."

She and her partner Wayne Walls, a 23-year-old cleaner, who live in Goodwood Way, Brighton, were shopping with their two children James, two, and Sophie, three.

Mr Walls said: "We were going through the checkout when James asked to go to the loo.

"This woman came up and said she would take him. She picked him up and I told her not to touch my son.

"She said he was her child. We thought it was a kidnap."

Maria pinched and squeezed the woman's arm and forced her to let the boy go.

After staff intervened the woman left the store. Police later identified her from CCTV footage.

The parents and police praised Asda staff for their vigilance and quick action.

Mr Walls said: "We were really shaken up by what happened. We won't be letting our kids out of our sight, not even in the garden."

A spokeswoman for Brighton and Hove police said: "We will be visiting the woman and offering her advice.

"It must have been a shocking experience for the parents and they did exactly the right thing. We all have to be on guard these days."

She said the woman would not be charged: "She took no steps and made no effort to leave the store with the child."