Police have confirmed that David Edward Cullen, 39, died of natural causes at his home in Asket Close, Seacroft, Leeds at the weekend.

Police originally arrested his partner but she has now been released without charge.

David Cullen, 15, died along with friend and schoolmate Christopher Copland, also 15 in June 2005. The pupils at Boston Spa School drowned in Waterloo Lake, at Roundhay Park, Leeds.

Mum Janine Roche, who divorced Mr Cullen, said the family was "absolutely devastated". She said her ex-husband had never got over losing David.

She said: "He was a very funny man. He made everybody laugh. Everybody loved him, as they did his son David. He was also a very kind person."

She said Mr Cullen was very much looking forward to the birth of his first grandchild, as her daughter Claire is pregnant.

Mrs Roche added that their younger son Daniel especially cherished memories of cooking with his dad.

"Claire says that he was never the perfect dad but his heart was in the right place and all his children knew he loved them," she said.

Tribute pages to Mr Cullen have been set up on a memorial website.

Following the deaths of David and Christopher, Mrs Roche and Christopher's mother Amanda Copland led a fundraising campaign for memorial stones at the places where they were pulled out of the lake.

Mr Cullen had been involved in that and several memorial events for his son and last month marked David's birthday with the rest of the family.