Health board officials have been forced to apologise to a former NHS trust director over the "shocking" delays in her late husband's cancer diagnosis.

Sandra MacKenzie said she believes her husband Bill, who died aged 75, could have survived had his condition not been inexplicably downgraded from "urgent" to "soon".

It meant the diagnosis of cancer was delayed by more than four months, and by the time he reached theatre it was too late.

The person who downgraded the call for treatment has not been identified publicly and a Scottish Public Services Ombudsman investigation has found earlier action "may have altered the prognosis for the better".

Tayside NHS Health Board had to apologise not only for that delay but also a second mistake after the ombudsman upheld two complaints by Mrs MacKenzie involving Ninewells Hospital, Dundee, and Perth Royal Infirmary.

Mr MacKenzie's case is the second in a matter of weeks to be highlighted by the ombudsman. The Herald revealed last month that a Cumbernauld woman is considering legal action over the delay in diagnosing her husband's cancer.

Sandra Wilson, 60, felt the death of her husband Ian, 63, could have been avoided if his cancer had been detected earlier by doctors. Professor Alice Brown, the Scottish public service ombudsman, upheld a complaint that, in Mr Wilson's case, the diagnostic process was unnecessarily delayed.

In the latest case, Mrs MacKenzie, 67, of Dundee, previously a non-executive director with a former NHS trust in Dundee, and her family were preparing for what they felt would have been a routine operation.

Mr MacKenzie, a businessman, was in the anaesthetic department in Perth when the consultant viewed for the first time a detailed CT scan taken six days before in Dundee. It showed the cancer had spread to his liver and was inoperable so the procedure was cancelled at the last minute.

Mrs MacKenzie said: "Firstly, if my husband had been diagnosed earlier I may have still have had him today."

She went on: "We were told there was something not quite right but nothing to worry about. Once they realised there was a cancer in the colon it was arranged that he would go to Perth for the operation. He was due the operation on the Thursday but the consultant wanted to see the scan before he operated which is fair enough.

"My husband had the scan on the previous Friday, but the consultant was not given the results until the day of the operation. Bill was in pre-surgery. Can you imagine the stress of being told it was inoperable?"

Mrs MacKenzie added: "The two hospitals were not in proper contact with each other. The GP referred him urgently to the hospital but it is terrible that it was downgraded before he even had a scan."

Mr MacKenzie died in October, 2005. While a consultant at Ninewells felt the delay would not have made any difference to the prognosis, a medical advisor to the ombudsman said if the process had been speeded up it "may have altered the prognosis for the better".

Ms Brown observed there had been a delay of three months before Mr MacKenzie had been seen by a consultant at Ninewells on May 4, 2004. A barium enema was performed on June 29 and the report on the procedure was acted upon three weeks later.

"The barium enema was highly suggestive of a malignancy and necessitated biopsies for microscopic examination at a colonoscopy which was performed on August 25, a further delay of one month. These investigations confirmed cancer of the ascending colon, the first part of the large intestine," said the ombudsman.

Mr MacKenzie was referred, after a further month, on September 23, to a second consultant at Perth for his surgical treatment. This was because his waiting list was shorter than that of the Ninewells consultant.

Ms Brown went on: "It was, therefore, reasonable to proceed to surgery as expeditiously as possible. A CT scan was then carried out on October 22, 2004. This unfortunately showed extensive spread of the cancer. In the ombudsman's advisor's opinion, the diagnosis of Mr MacKenzie's cancer was delayed.

The professor added: "The board, in a written enquiry from the ombudsman's office, were asked who had triaged the referral from the GP to Ninewells Hospital in January, 2004, and why the referral had been triaged as 'soon' rather than 'urgent'.

"The board ... stated that they were unable to provide the name or designation of the member of staff who triaged... from 'urgent' to 'soon' as a signature has not been provided on the triage documentation."

NHS Tayside Health Board accepted recommendations to review procedures.

It said that, after Mr MacKenzie's referral to the hospital, a fast track procedure to deal with referrals of suspected cancer patients was implemented.

A new procedure requires clinicians to complete a form if they are downgrading any patient referrals.