The Grand Tour producer talks bringing down the chequered flag on its motoring musketeers

The fourth musketeer – and, like D'Artagnan, arguably the most important – says they didn't want to go out with a trademark big bang, but a warmly affectionate celebration of their friendship. And that's true. At times this final Grand Tour special feels like a love story that's taken two decades to consummate.

"With this one we felt we should leave the dynamite at home, that no high jinks should get in the way of them saying goodbye," says Andy Wilman, the creative, behind-the-camera powerhouse for all those 22 years. "It's more gentle, more reflective and I think they brought their A game with their conversation and their banter, which was wonderful. Their friendship is fully on display."

The depth of that friendship – underpinned by merciless mockery – is evident like never before. Richard Hammond will do well to unburden himself of the nickname Buttons, so called because of Clarkson and May's conviction that he will serve out his post-programme life in panto. That said, he does get to deliver one of the best lines of the show as he reflects whimsically on its demise. "We don't have to all go to the same old folks' home, do we?"

It brought Wilman to tears, mostly the laughter sort. "I thought, 'I love you three, because only you three can say goodbye in this way. You are clearly sad, but you are robust about it. You are taking the piss to the very end.'"

The backdrop to this final outing – and at two hours and ten minutes it’s a very long last lap – is an east-west drive across Zimbabwe in the three cars they've always wanted to get behind the wheel of – a Lancia Montecarlo (Clarkson) a Ford Capri (Hammond) and a Triumph Stag (May).

It ends with a cross-border dash across the salt plains of Botswana to Kubu Island, a crescent-shaped area of rocks they last visited 17 years ago and a place they still cherish.

As Wilman indicates, there are very few stunts. A VW Beetle is ritually sacrificed in an outrageous piece of mountainside theatre and there's a moment when the programme trolls itself with Clarkson being reprimanded by May for describing the inside of his car as "like the black hole of Calcutta". "You can't say that," May tells him, concealing a smirk.

There are plenty of mechanical breakdowns and just as many ingenious solutions. There's also breathtaking scenery – perhaps it's a sign of his countryside conversion that Clarkson sighs longingly at the beauty of the Jacaranda trees outside Harare.

The question is then, why quit now? Back to Wilman. "I think the most important reason, certainly for me, was that I know we're past our peak, but we're still standing and we're still wanted.

"So, the natural thing then is to go – wouldn't it be amazing if we land the plane under our own terms rather than pilot it into a mountain with the viewers all going, 'Would you please just f**k off?' So, I'm very pleased that we've brought it to an end on our own terms and I'm very pleased that we will have an audience to watch it."

Read more:

• Jeremy Clarkson says Top Gear wouldn't get made now with "3 middle-aged, middle-class men"
• Jeremy Clarkson reveals why he quit The Grand Tour after 8 years

Wilman says that he attributes the audience's affection to the on-screen chemistry created among the three presenters, but it's right to say that's due in no small part to his special brand of editing alchemy.

"As humans they're all on the same wavelength and are all fantastic at self-deprecation. They are male but they are never macho. If we'd had somebody macho that would have been a disaster. And they are not that. They came as a package that was very charming.

"And I am massively generalising here, but girls do find nerds attractive. And that was Richard, James and Jeremy. People thought they were like Morecambe and Wise living in that house together in their striped pyjamas – slightly weird and harmless but quite funny."

For a man who professes to be only "moderately interested" in cars and who failed his driving test three times, Wilman is an unlikely flag-bearer for Top Gear and, latterly, Grand Tour. But both shows bear his formidable imprint.

In the 1990s, he was a presenter on one of the many incarnations of Top Gear, having been given a significant professional leg-up by his Repton schoolboy chum – and since lifelong friend – Clarkson.

Wilman says that their shared experiences at Repton helped create the template for the Top Gear show they were to revive for the BBC in 2002 and subsequently with Amazon for Grand Tour after Clarkson was sacked by the BBC in 2015. "We both had egos and wanted to be liked and noticed.

"We could make people laugh by getting into trouble. We were funnier than most with our getting into trouble and that carried on into the shows we made."

Wilman accepts now that some of the trouble his Top Gear created was regrettable. Though if you'd like a fulsome apology he's probably the wrong person. "Sometimes we stepped over the line and we did need a proper slap, but most of the times when we got into trouble, the viewers were like, 'Well, nobody's died – it's fine.'

"None of our shows were ever going to be vanilla. The amount of times people would say, 'Oh, would you do electric cars or alternative transport?' for balance. And you're like, 'We're making a f**king car show. Do the Two Fat Ladies do balance – do they make a salad after they've made a steak and kidney pie?' You know good telly only exists without balance. Leave that for the news."

If you detect a bullish streak in Wilman's otherwise cheerily matey demeanour, you'd be right. He made it clear ahead of the interview that he had no interest in picking out highlights. So, what about low lights? He strikes a more sombre tone as he recalls the 2006 crash that almost cost Richard Hammond his life. "It's still burned in my brain.

"I have never felt fear and panic like that. You are completely helpless and completely angry and frustrated that you're making an eight-minute TV item and he's a father, critically ill in a hospital bed."

There are clear parallels with Freddie Flintoff's accident, which caused the BBC to suspend production of Top Gear. Does Wilman think it will come back? "What happened to Freddie was terrible and it's wonderful to see him back [with Freddie Flintoff's Field of Dreams].

"Top Gear coming back is a different question. I don't think the BBC has the will to make a car show. I don't think they're interested in the topic, or that there's anyone interested in doing it."

Meanwhile, the closing scenes of this Grand Tour episode provide a fitting finale to the adventures of Clarkson, May and Hammond (the show is set to continue on Amazon Prime Video with Wilman involved but with new hosts). As all three race across the Botswana salt plains – car doors off, goggles and face scarves firmly in place for protection – Dire Straits' Brothers in Arms provides the soundtrack.

Then, as the credits roll, with informal shots of the production team hugging and shaking hands, it's George Harrison's My Sweet Lord that plays out. Says Wilman: "I wanted something that had melancholy but that was uplifting and said, 'Hey, we had some great times,' and I thought My Sweet Lord did that. It gives you permission to lift. It's so beautifully written – you'll still have a tear in your eye."

It was, says Wilman, a "weepy" last few days of filming. Even the normally stoney-faced Clarkson was moved. "The saddest I've seen Jeremy was when I sent him a cut of the film and he watched the ending and that really shook him."

Wilman likens the production to a touring band – each series is a new album, each episode a new track. We continue the music analogy and I ask which band would Top Gear/Grand Tour be. The Beatles perhaps? He counters, laughing loudly, with "Eddie and the Hot Rods. I don't want a headline quoting me saying, 'We're as big as the Beatles.'"

And, like all bands, presumably there were some disagreements? "We were grumpy at times and probably got on each other's nerves, but it was still a very tight, close-knit band – we would turn on anybody who came near us from the outside. It's a dysfunctional set-up, but it's our dysfunctional set-up."

So is he certain that this Fab Four won't reunite for a 'one night only' revival? "There won't be any Status Quo farewell tour. There really won't.

"We were scared we were running out of ideas. Jeremy says, 'I'm 63 and I've got a granddaughter,' and he's so happy on the farm. We will never do this again, but how lucky have we been."

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