The story hit the headlines last August when Carol Ann Park's body was found by -amateur divers at the bottom of Coniston Water in the Lake District.
Her former husband, Gordon Park, 53, was on a walking holiday in France with his new wife Jennifer at the time, unaware of the discovery, and was arrested and charged with murder shortly after he returned to Britain.
Mr Park had been awaiting committal for trial next week on the murder charges when the Crown Prosecution Service announced yesterday that the charges were being dropped through lack of evidence.
In a statement the CPS said lawyers had carefully reviewed the circumstances surrounding Mrs Park's death before reaching the decision. "After a conference with leading counsel and the police, a decision was taken, in agreement with all parties, that there was insufficient evidence for a realistic prospect of conviction."
Unusually in such a difficult case, Cumbria police decided to charge Mr Park, who now works part time, without first seeking the advice of the CPS, whose job it is to decide on the likely success of any prosecution.
It is understood the key problem was the lack of forensic evidence obtained from a body which had been underwater for 21 years.
Last night Mr Park's solicitor, Barbara Forrester, said he was "very much relieved" by the news, and appealed for privacy for him and his family. She said he had always maintained his innocence. It was too soon to consider any civil legal action by her client, she added.
Mrs Park, also a primary school teacher, was 30 when she vanished from their home in Leece, near Barrow. She had not been regarded as a murder victim until last August when the divers found her body, still wearing a blue baby-doll nightdress, bound and weighted in 70ft of water.
Before charging Mr Park with his first wife's murder, detectives had searched his home and a boat he kept moored on Coniston Water, where he had been a keen sailor for many years.
Mr Park, married three times, was granted bail on condition that he lived at an address in Tyldesley near Manchester while awaiting committal. The couple's grown-up children, Vanessa, who was eight when her mother disappeared, Jeremy, then six, and Rachel, then five, were interviewed by specialist officers to see if they could recall anything about the last time they saw their mother alive.
The family had been due to visit Blackpool on a day trip when Mrs Park said she felt unwell and wanted to remain behind in bed. She was never seen again.
Cumbria Police said last night they had not closed the case, which would continue to be "actively investigated".
Detective Superintendent Ian Douglas, leading the investigation, said: "Work will continue in an attempt to bring this case to a satisfactory conclusion.Reuse content