After the case Mr Cooper said he was very pleased

Mick Cooper, 56, from Chippenham, Wiltshire, took on the case against the Royal United Hospital Bath, NHS Trust.

Helen Cooper, 51, died on 21 September just days after giving evidence as part of a case alleging medical negligence.

On Wednesday the High Court in London ruled that doctors had breached their duty to Mrs Cooper.

Mr Cooper, a nuclear engineer, stepped in to fight the case on Monday at the Royal Courts of Justice in London.

Mrs Cooper, a health visitor who worked for the NHS for 34 years and was diagnosed with breast cancer in May 2002, had begun the claim.

I would like to take this opportunity on behalf of the trust, to extend our deepest condolences to Mrs Cooper's family Mark Davies RUH Bath NHS Trust's chief executive

Bath NHS Trust had denied liability.

The case put on her behalf was that, following an "indeterminate" biopsy in July 2000, it was not made clear to her that there was a risk that she might have breast cancer and that the preferred way to be sure of that was to have a further biopsy.

The issue the judge had to decide was whether Mrs Cooper was adequately informed and advised when the decision was taken not to undertake a further biopsy but to monitor her by repeat mammography.

Mr Justice Butterfield ruled in favour of widower Mr Cooper on the issue of breach of duty - finding that there was a failure to adequately advise his wife of the risks she faced, the options open to her and their respective merits.

However, the court has yet to decide whether a second biopsy would have located cancer.

Mr Cooper said he was "relieved"

After the judgment, Mr Cooper said: "I'm very very pleased for my wife, and hopefully it will help other people undergoing the same treatment as her.

"My wife fully believed in the NHS and that everyone should get the best out of it.

"It is a great relief that justice has been done.

"I think the trust treated my wife very, very poorly - I can say no more than that.

"I will sleep tonight. I did not sleep last night or the night before. It's been a tremendous relief for myself and my family.

"It is a great relief that justice has been done."

The RUH Bath NHS Trust's chief executive, Mark Davies, said: "The trust takes this issue very seriously.

"We will need to read Mr Justice Butterfield's judgement very carefully in order to assess the next steps and to take appropriate action.

"I am determined that if there are any lessons to be learned we will learn them but I am confident this was an unusual and tragic one-off case.

"This said, I would like to take this opportunity on behalf of the trust, to extend our deepest condolences to Mrs Cooper's family."