“I don’t think it’s real. You didn’t just dream this, did you?,” Fred MacAulay dismisses the mind-boggling notion that such a monstrosity of road engineering as the Magic Roundabout could actually exist.

The line goes eerily silent and I fear he has had enough of this perceived ‘leg-pulling’, until finally I make out some shuffling and tapping sounds. Google has been called upon to settle things. “Oh my goodness, that is horrific,” he booms at last. “I might leave the car and take the train,” he adds aghast.

As far as comics go, Fred MacAulay could be described as the pragmatic kind. The Perthshire-born stand-up and radio presenter relies on indisputable evidence and, at one time anyway, cold hard numbers.

“I got a degree in accounting,” he says casually. “I thought I would earn a few bucks.

“I wanted to go into comedy but I grew up in rural Perthshire and I had no idea how people would go into comedy or entertainment.

“I was an accountant for a good while. Then I got to 30 and thought, ‘That’s a whole decade gone by. I should do something about the comedy’.”

Eventually he took the plunge and entered an open mic competition in Glasgow in 1988.

“I didn’t even get into the final but I knew that’s what I wanted to do,” recalls the 58-year-old. “I just hadn’t a clue what to expect. The first time you grab a microphone is odd. And then you think the lights are bright, I can’t see the people in front of me. I had taken a non-alcoholic beer with me in case I had a dry mouth and I kind of remember doing an ad lib about non-alcoholic beer. That’s what got the most laughs.

“We were dead lucky because there was a chap there from just outside Glasgow who had a pub and he wanted to put on a stand-up show and the deal was you’d come and do five minutes and if the five minutes worked you’d be allowed to do 20 minutes the next month and you’d get paid. That’s how it started. “ As his street cred grew, BBC Radio Scotland came knocking offering him to take over one of its shows. He initially signed a three-year contract. He bowed out in spring after 18 years.

Not a day went by that he did not have to diligently go over the golden rule in his head before hitting the microphone: “Don’t say the ‘F’ word,” he deadpans. “That’s what goes on in your mind. I do swear a lot, and I swear on stage. I don’t think it’s clever but it’s something I do. And the BBC doesn’t have that seven second delay.”

Now, for the first time since 2012 and just a few months after ending his long-running stint presenting MacAulay and Co., the comic is back on tour.

He is still juggling other radio gigs, including a regular panellist slot on Radio 4’s The News Quiz, but admits now that the children are grown up he has more freedom to scamper off to the four corners of the nation – in theory at least.

“It’s a good time to be back on the road. We are at the stage where my kids are all grown up and employed. They are all supposed to be away from the house, but some seem to be hanging on.”

As a comedian who thrives on his audience’s raw response, he says there is nothing more rewarding than the immediacy of stand-up.

“It’s the most immediate reaction in the world. You can’t pull the wool over anybody’s eyes. If you’re not cutting it there’s no hiding place. You can hear a pin drop.”

His latest show, Twenty Fifteen, won’t skirt controversial issues as he ponders how his country will shape up after the referendum of 2014. As well as looking backwards and forwards at politics, he’ll also look sideways at sport, the environment and the concept of ‘celebrity’.

“There is a very simple sentence that will tell you whether someone thinks they’re a celebrity or not: ‘Do you know who I am?’”

Delightfully self-deprecating he is keen to point out the show took “the best part of two to three years to come up with”.

“If it was easy to make things funny, I would be Billy Connolly,” he quips. “There is a fair bit of anecdotal stuff and I’ll be honest, some of it is pretty silly. Nobody is going to have their opinions changed, but I hope they have a bloody good laugh.”

He has a secret weapon to bowl over audiences - and it is fair to say his trump card beats Billy Connolly’s hand any day.

“I can tell 50 varieties of potatoes by the shape and colour of their leaves as they are growing in the field and if they have a disease I can tell what the disease is. I don’t suspect this is going to come up in the show.”

And then again, it might. If ever there was an invitation to bring your ailing buds for a thorough examination, this is it.

Fred MacAulay is at the Arts Centre on October 7 at 8pm. Book at swindontheatres.co.uk or call 01793 524481.