Sir Cliff has enjoyed a 52-year career and never married
Sir Cliff Richard dumped his first serious girlfriend by letter, saying he had to put his pop career before any "lasting relationship".
Britain's "Bachelor Boy", then 21, wrote the letter to dancer Delia Wicks from Australia where he was on tour. The pair had been dating for 18 months.
In the letter, Sir Cliff said "showbiz was in his blood".
The 150-word handwritten missive has been published following the death of Sir Cliff's ex-girlfriend from cancer.
Sir Cliff, who is 70 this year, is probably Britain's best known bachelor, with a 52-year career as a singer and an actor.
He is also the biggest selling UK singles artist of all time, with total sales of more than 21m.
Last year, he reunited with The Shadows for an arena tour.
The letter, written in October 1961, misspells Delia Wicks' name as "Dellia".
In it Sir Cliff writes: "Being a pop singer I have to give up one priceless thing - the right to any lasting relationship with any special girl."
Sir Cliff in 1962
He also said it was "one of the biggest decisions" he would ever have to make.
The singer urged her to "find someone who is free to love you as you deserve to be loved" and who "is able to marry you".
He continues: "I couldn't give up my career, besides the fact that my mother and sisters, since my father's death, rely on me completely.
"I have showbiz in my blood now and I would be lost without it.
Delia - who performed in the then-popular Black and White Minstrel Show - was said to have been heartbroken by Sir Cliff's decision to break off the romance.
She went on to marry company director John Pyle in 1970 but later divorced.
After she retired from the stage, she worked in a shoe-shop in Warwickshire.
The letter was made public by Delia's brother Graham Wicks following her death from cancer, aged 71, last weekend.