Mayall is not exaggerating. He is a man who cheated death in a near- fatal accident. It's the sort of disaster and bizarre recovery that would fit perfectly into a script featuring his manic TV alter-ego Richie from Bottom, who, teamed as usual with Ade Edmonson's nutter Eddie, has now been transferred to the movie screen in Guest House Paradiso.
Mayall affirms that he has made a complete recovery from the accident in April 1998, when he fell off a Quad four-wheel bike at his Devon farm and was found unconscious with blood seeping out of his nose, eyes and ears. His skull had been cracked but the skin was not broken.
When he awoke five days later he was confused and unable to speak. Blood was clogging up his brain. He was sure he should not be in hospital and attempted comic escapes like taking wrong turnings when on walks with nurses and running to a door only to find it locked.
On arriving at a private hospital in London's Harley Street he gave an attendant the slip, ran into the street, hailed a cab and got back to his London home. A doctor was called who gave him an injection and the next thing he knew he was waking up at Charing Cross Hospital.
He dates his recovery to a two-day deadline given by a surgeon before the top of his skull would have to be lifted so that the excess blood could be drained from his brain. "I went home and worried, worried, worried about it, and the next day it was gone. Whether that's a medical technique I don't know, but it was all clear. "
But he was still confused and forgetful. He recuperated over the summer of 1998 and in September started working - first on voiceovers, then in an episode of Jonathan Creek - and went to South Africa to act in the yet-to-be-released movie Merlin 2000.
He was put on medication because of the risk of epilepsy, but after a few months saw no point in taking the pills - and anyway he fancied a drink. Another Bottom-esque incident ensued. His wife Barbara came home to find him shaking up and down on a bed. Aghast at apparently discovering him maniacally masturbating, she went in and saw that he was biting his tongue, which was bleeding. "She thought, 'What a relief; he's having epileptic fit.' It's true. What more love could a man want? So I ended up in hospital again."
He says that he has recovered 100 per cent of his mental capabilities. There are minor memory lapses where he admits he might be "a little vague, a word might evade me". But it is in his relationship with Ade Edmonson, his partner of 25 years, that the balance of power appears to have subtly but decisively shifted, despite his assertion that the only thing that has changed is that they are now even closer. When Mayall was half or three-quarters recovered - his own assessment varies - they finished trimming the script Guest House Paradiso down from more than three hours to some 90 minutes and then they started discussing possible directors. They soon realised that there was only one suitable candidate.
Their relationship is such that Edmonson would never have put himself forward. "We don't behave like that. It's just not done. I think it must have come from me. He must have thought, 'hey, maybe I can do it' as I thought 'why don't you do it?' It sort of happened in the conversation, but it seemed obvious. He's much too - proud is not the word - too honourable to suggest himself. And I don't think he was ever planning it all along."
There was no question of Edmonson taking advantage of his friend's weakness. Though that did not stop Mayall mercilessly ribbing him. "I called him the dear leader after that." And Mayall raves about how brilliant a job Edmonson made of directing his first movie..
The resulting film sees what Mayall refers to as more three-dimensional characters exploring their inner Tom and Jerry selves. Richie and Eddie are running a hotel from hell set in a bleak corner of England next to a leaking nuclear power plant.
The characters are drawn and acted so well, he says, because they are so close to him and Ade. Behind the comedy he sees a connection to the bleakness of Samuel Beckett. "It's all unconscious, but it's a kind of tone that attracts or suits us. There will always be two guys who don't fit in, don't belong. Perhaps there's something similar that humanity, all individuals feel. That bleak edge of the cliff top."
In a recent three-week burst of creativity Mayall and Edmonson wrote their first draft for what they hope will be their next film and whose theme Mayall wishes to keep quiet, though Edmonson has spoken of a space ship full of shit.
"I have an uncontrolled imagination which sometimes is merely wittering. When Ade and I are together he says sometimes, 'shut up about it, go make the tea'. And I go make the tea while he's writing down what we've just been talking about because I don't listen enough."
Mayall says he now has more concentration than he used to, which may be true in short bursts, but as our interview wears on, his mind wanders off more and more.
"At funny times during the day memories will come to me. I might be in the shower and I can suddenly remember something from primary school, like walking around a particular corner or seeing a face from years ago or a phrase that someone said when I was on holiday when I was 13..."
His professional future he sees as consisting of more films, as Edmonson's stature as a director grows, more of the same mix of serious and comic roles, and the possible fulfilment of his ambition to bring Beckett's Waiting for Godot to the screen.
He's happier than ever, even closer to his already close family of wife Barbara and three children. He feels that there's an element of being given a second chance, though he doesn't think life fits so easily into such categories.
"Sorry to be dull, but I'm just happy. I think I'm a better actor as well, in my mind, because I've experienced more. I'm not saying all actors who want to be better should go throw themselves on a Quad bike, but imagination can be helped by experience. I think I'm relieved at last, because of my age. I think it maybe hurried my... oh bollocks, you're the writer. What's that thing that men have when they're 40?"
He's having one of those memory lapse moments. I proffer male menopause.
"Menopause. Yes, thanks," he replies. "I think that's been hurried. I feel mature now."