He was born in Omaha, Nebraska, on October 17, 1920, soon after his twin sister Roberta - later named Ethel. Their older brother was Brooks, their father William Brooks Clift, a banker with Southern roots, and their mother Ethel Fogg Clift, known to everyone as Sunny. And it was she who would have the dominant impact on Monty's life. She had been adopted as a baby, the illegitimate child of two members of leading American families and it was only as a teenager that she discovered her father was Woodbury Blair - the son of Montgomery Blair, postmaster general in Lincoln's cabinet. Her mother was Maria Anderson, daughter of Colonel Robert Anderson who led Union forces in the Civil War. Soon after her birth she was handed to family friend Dr Edward Montgomery before being adopted by the Foggs. She would spend much of her life trying to be recognised by the families as their offspring.

The family lived well and moved to Chicago early in Monty's life. They enjoyed long holidays - often without William Clift - and Sunny preferred to teach the children herself. When he was just eight, Monty and his siblings were taken on the first of what would be several extended trips to Europe - again without their father. They stayed in fine hotels, were taught by private tutors and were kept apart from other children. In her biography, Patricia Bosworth says this was the result of Sunny Clift's plan for them to be accepted by the Anderson-Blairs but Brooks later called this an oversimplification of his mother's motives.

The 1930s would bring tough times for the Clifts. William's business suffered, they moved to smaller accommodation in New York and the long vacations came to an end. In 1933, Sunny took her children to Florida with their private tutor Walter Hayward and settled for a time in Sarasota. It was there that Hayward got Monty a small part in an amateur production of the Rachel Crothers' comedy As Husbands Go. It was his first performance on stage but the imaginative Monty was no stranger to performing - as a child he regularly staged small plays for his family.

With their father now back on his feet, the family returned to live in Manhattan, where Sunny dispensed with her earlier plans to put her favourite child into one of the professions and instead began visiting agents in an attempt to win auditions for her son. He was also signed up as a model, a job he would hate but was perhaps the start of his life-long passion for photography. In 1934 Monty was cast at the last minute in a summer stock production of the comedy Fly Away Home. He proved so successful in the role of Harmer Masters that he was engaged for the Broadway run beginning in January 1935. Later he was cast in the much-hyped musical Jubilee.

While Brooks and Ethel were sent off to school to prepare them for the best universities, Monty continued to rely on a private tutor apart from a brief stay at the Dalton School in New York. He never earned a high school diploma - something he seems to have regretted throughout his life - and Sunny's motives here remain unclear. Was it because she had determined that her son was going to be a great actor and needed little more in the way of a formal education? Or was it because this powerful woman wanted complete control over her son's life?

He resumed his Broadway career at the age of 17 and found himself in several commercial failures. The only bright spot for him were the favourable notices his performances tended to attract. Dame Nature, which opened the Theatre Guild's 1938-39 season, earned him much praise and was his first major role but it's light-hearted nature didn't seem to fit in in a world where the Nazis were on the march in Europe and it lasted just 48 performances.