A 42 year-old father of six with no history of connection with drugs is thought to have died of a heroin overdose.

Yesterday, as police were still trying to trace his last movements, a detective said: "This is a real tragedy."

Graham Midgley collapsed shortly after enjoying tea with his family at their Staveley Grove home, in Ingrow.

Paramedics battled for about 30 minutes to try and revive Mr Midgley, a builder by trade, but he was pronounced dead on arrival at Airedale General Hospital, Steeton, on the evening of Thursday, April 12.

Detective Constable Neil Davis said: "The family are absolutely devastated. This is a real tragedy.

"We need to find out about his movements on the evening of his death. I urge anyone who knows anything to contact us."

He stressed that the death was not linked to the two other suspected drug related deaths in Keighley a month ago.

"Mr Midgley has no history of any connection with drugs -- we want to stress that.

He was a happy, family man who was close to his children."

He had enjoyed a meal at tea time with his family when he collapsed. Everything had seemed fine before that," said Det Con Davis.

"We are treating it as a sudden death in suspicious circumstances and we suspect a heroin overdose."

Paramedics were called to the house and spent about 30 minutes trying to revive him.

"His family want to thank them for their efforts to save him," he added.

Mr Midgley had not been working recently because of illness, but he was passionate about potholing and caving.

He had been involved in cave exploration and had discovered a cave in the Yorkshire Dales. He had also been involved in potholing abroad.

Mr Midgley had three young daughters, Jessica, Emma and Wendy, aged 11, 13 and 14 who lived at home with him and his partner, Beverley.

He also had three sons Leon, Daniel and Lee.

Detective Superintendent Philip Sedgewick, who is leading the investigation said: "In cases like this we have to look as to whether they administered the drugs themselves or someone did it for them.

"Often the people who are most vulnerable to overdoses have a very low tolerance."

A 42-year-old man was arrested on a drug related offence following Mr Midgley's death. He was released on police bail pending further inquiries.

Anyone with information is asked to telephone Keighley police on 01535 617085.