At 85 years old, Elliott Erwitt feels no need to impress.

His reputation as one of the greatest living photographers has long since been cemented. It is a description that makes him embarrassed rather than proud but it does mean Erwitt stopped having to sell himself or his pictures long ago. So when I ask him how he chose the 158 photographs for his new book, Elliott Erwitt's Great Scottish Adventure, I am met with a somewhat bewildered, if not quite curt, response. "I would say I like most of them because otherwise I wouldn't have chosen them."

You can't argue with that.

The pictures form part of a portfolio that includes Jackie Kennedy in mourning at her husband John F Kennedy's funeral and a young Marilyn Monroe - magical in monochrome - on the set of The Misfits.

But it was his latest brief, to capture the essence of Scotland - its diversity, character and the things that make it world-renowned - that saw him travelling around the country in an old Bentley, driven by the art director of the book, taking pictures of anything that caught his eye.

What started as a 10-day commission, in collaboration with The Macallan whisky as part of its Masters Of Photography series, became 38 days in total, done over three trips. He spent most of his time on the mainland, starting in Glasgow and Edinburgh then heading to the Highlands, before coming back to shoot the islands, making it as far north as Orkney. He was particularly impressed with Skye, which he found beautiful. Ask him why he accepted the project and he will give you a logical response. "Because that's what I do for a living," he replies. Later, he expands on this. Clients normally have a clear idea of what they want, he says, but this commission was unusual in that it gave him the freedom to do what he wanted. "The opportunity to do any picture that strikes me was a marvellous opportunity."

Erwitt was born in Paris to Russian parents. At the age of 11, his family settled in New York. By 1941, he was in Los Angeles. By the end of that decade, he was mingling with renowned photographers such as Edward Steichen and Robert Capa, the founder of Magnum Photos, who invited Erwitt to join the group. To this day, he still works with film and is famous for his observational photographs that capture the mundane and the majestic in everyday life, with a twist of humour.

The book's most captivating images are those that convey this element of fun. For this he enlisted the help of a stuffed gorilla - "it sounded like a good idea at the time," he says - and, later, constructed what appeared to be a Loch Ness monster, with the help of a little photography magic - and not digital manipulation. That's not his thing.

Other photographs that stand out include one of Erwitt's favourite subjects: dogs. "We were able to assemble 12 Scottish breeds," he proudly tells me.

And while he undoubtedly captured his share of stereotypical images of Scotland, Erwitt insists he embarked upon the project with no preconceptions. He would find the frame, wait for something to happen, for someone or something to walk into the shot. At the Barras, Glasgow, he positioned himself in front of a snack bar. "It was just a matter of waiting for some human evidence to give it scale and context."

With only a loose itinerary, most images are the result of "ad hoc encounters", he says, telling me that travelling around Scotland in a temperamental Bentley in unpredictable weather made for some humorous moments, not least when they couldn't get the car to start. "Sometimes it worked, sometimes it didn't. It was all part of the comedy." As for the weather, he concedes that to photograph Scotland only in sunshine would be "silly" and praised the long, light-filled days of Scotland's late summer and early autumn.

Despite being in what you could call the twilight of his career, Erwitt says he gets the same joy from taking a picture as he always has. "It's been a good long ride and I have enjoyed most of it." What keeps him going? "I don't know," he answers. "You have to do something in life. You can't just sit around."

Given his age, I wonder if he is at a point in which he can reflect on his career. Yes is the answer - but Erwitt is still looking to the future. He likes doing books - "because I'm not pressured into doing things I don't like to do" - and wants to do more in the future.

No plans to stop? "Erm, yeah," he chuckles. "Maybe when I'm on the other planet."

Whatever that means, it is Erwitt's belief his time here on earth was best served being a photographer. "There was never another option." As for what he hopes his Scottish pictures convey about the country, he says: "I hope they reflect the character of the place in a small way - the look of it, the feel of it. And if they do that, then I guess I have been successful." n

Elliott Erwitt's Great Scottish Adventure is available in a limited-edition package including a 35cl bottle of The Macallan for £1000. See