A mother who died when a swollen gland in her neck burst was due to have a routine operation three months earlier which could have saved her life.

Oxford Radcliffe Hospitals NHS Trust is now investigating why Ertrice Simmons, 56, of Blackbird Leys in Oxford, did not receive the operation she was promised.

The mother-of-10, of Pegasus Road, was due to undergo treatment on an enlarged thyroid in her neck in August last year. But she died at her home in November - three months later - when the thyroid gland burst.

Now, a year after her death, her daughter Annica Simmons-Bobb, of Teal Close in Greater Leys, is demanding an inquiry into why she was not treated.

A letter from the trust to Ms Simmons-Bobb said in April last year it was recommended her mother should have the operation before August 21 - but the surgery was not scheduled until the following January.

A trust spokesman said it could not explain why the operation was not carried out.

Ms Simmons-Bobb said: "I know no reason why she wasn't seen. She should still be here alive today but because of that mistake she is not.

"I want justice. I know had it been the other way round she wouldn't have just left it like that.

"I want them to admit to being responsible. Death from an enlarged thyroid is extremely rare.

"I'm not looking for compensation, just for someone to say 'yes we did do this wrong and we are putting things in place to make sure it doesn't happen again'."

Doctors diagnosed Ms Simmons with a swollen thyroid gland in 1995.

As the swelling got worse it limited her breathing and she was referred to specialists at the John Radcliffe Hospital in October 2004.

The following January a consultant recommended a scan and results in April 2005 revealed she required an operation.

The letter from the trust shows that if the operation was held by August 21 it would have been within the trust's four-month waiting list policy.

After the death doctors told Mrs Simmons-Bobb they could not recall another fatality in Oxford caused by a swollen thyroid in the neck over the past five years.

A trust spokesman said yesterday officials were trying to find out why the operation had not gone ahead in the August. He added: "We are currently investigating the circumstances around the fact that Ms Simmons was not operated on within the timeframe given by the trust.

"We are determined to resolve this issue for the family of Ms Simmons."

Divorced Ms Simmons worked as a scout at Jesus College and an assistant at the Radcliffe Infirmary. She had lived in Blackbird Leys since 1989, where she was a regular at the Holy Family Church in Cuddesdon Way.

Her daughter said: "She was very hard working and always full of life and very happy. People would recognise her laugh - you often heard her laugh before you saw her.

"She was very caring and a sensitive person towards people's feelings and always there to listen."