The 80-year-old is officially the biggest-selling non-fiction writer in history and was recently awarded an honorary degree from Leeds University - where he gained a bachelor of science in botany.

Essex-based Dr Hessayon grew up in George Street, Salford, with brothers Arthur and Leonard and sisters Jean and Miriam.

Arthur and Celia still live in Manchester, while Miriam lives in California.

Dr Hessayon, who attended Salford Grammar School, said: "A lot of good things have happened to me, but I like to think that I haven't changed."

His Expert gardening guides have sold more than 50 milion copies worldwide, translated into 22 languages and his latest publication, The Bedside Book of the Garden, is due out in December.

Recalling his parents' small garden in George Street, the size, he said, of "four pocket handkerchiefs", a small garden was more work than a large one.

He said: "It is like a window box. You fight to save every plant. If you lose one, it is like a death."

Dr Hessayon said he decided to write books when he was five.

And he debunks the myth that gardening is solely for elderly people.

"That is nonsense - it is becoming more and more popular among youngsters, especially growing vegetables," he explained.

He lectured in horticulture in Ghana before gaining a PhD in botany at Manchester University.

Dr Hessayon's first book, Be Your Own Gardening Expert, was published in 1959 and half of all the gardening books sold in the UK are written by him.

He was married to the late Kentucky-born novelist, Joan Hessayon and has two daughters and four grandchildren.

Dr Hessayon returns to Manchester "two or three times a year", and will be paying his next visit at the end of August when brother Arthur celebrates his diamond wedding anniversary with wife Celia.