He told the BBC Today programme: “He was happily chatting away [to my son] and then we still don’t know quite what happened but it was a seizure of some sort.
“He had 16 years after the quad bike and I think that at the time people didn’t think he would survive.
“But he lived for another 16 years and it was just shocking that he was so happy and seemed so healthy when he did go.”
He added: “He’s got a very wonderful family, he was a very loving father and all I can say is that Rik had a very happy life.”
Although Mayall defied the doctors to make a good recovery, returning to work the year after his accident, he was left with epilepsy for which he had to take daily medication. He had spoken in the past of suffering a fit after failing to take the pills.
His wife said she did not know how he had died.
Speaking outside the couple’s home in Barnes, south-west London, Ms Robbin said: “We don’t know yet what happened. He had a strong heart, so I don’t think it was a heart attack. But we just don’t know until the coroner’s report.
“Maybe he had a fit, maybe it was his heart. We just don’t know.”
Mayall and Ms Robbin, a make-up artist, married in 1985. They have three children.
Among those to pay tribute was Ade Edmondson, Mayall’s writing partner and co-star in The Young Ones and Bottom.
Their friendship dated back almost 40 years, to the day they met on a university drama course in 1975.
In a statement, Edmondson said “There were times when Rik and I were writing together when we almost died laughing. They were some of the most carefree stupid days I ever had, and I feel privileged to have shared them with him.
“And now he’s died for real. Without me. Selfish b——.”
One of the pioneers of the 1980s alternative comedy scene, Mayall found fame in The Young Ones, an anarchic sitcom in which he played a wannabe student radical.
He and Edmondson were also members of the Comic Strip Presents team alongside Dawn French, Jennifer Saunders and Alexei Sayle.
Other famous roles included Lord Flashheart in the Blackadder series and Alan B’Stard, the gloriously sleazy Tory MP in The New Statesman. The latter ran from 1987-1993, earning a Bafta and an Emmy award.
Mayall also appeared in film, starring in the Hollywood film Drop Dead Fred. He was cast as a poltergeist in the first Harry Potter film, only to find his scenes had been consigned to the cutting room floor.
With typical humour, he laughed off the slight. “That was the best film I was in – and I wasn’t in it,” he said.