EXCLUSIVE: 'I had a crush on her': Sound of Music's Nicholas Hammond reveals he fell for co-star Charmian Carr while filming iconic movie but says she was too busy drinking with Christopher Plummer

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It was the fairytale classic that saw mischievous nun-turned-governess Maria fall for the very dashing Captain Von Trapp and his seven children.

But behind the phenomenon that was to become the Sound Of Music, hearts were broken as several of the seven most famous children in the world fell in love with their co-stars.

While the actress who played Liesl (Charmian Carr) once admitted she had a crush on her on-screen father, Christopher Plummer, her movie brother Nicholas Hammond had fallen hopelessly in love with her.

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Unrequited love: Actor Nicholas Hammond, now 64, who played the eldest Von Trapp brother Friedrich in Sound of Music, reveals he developed a crush on co-star Liesl (Charmian Carr) while filming the 1965 movie

In love with someone else: But Charmian, the actress who played Liesl, was preoccupied with the exceptionally good-looking Christopher Plummer, who played her father Captain Von Trapp

He told Daily Mail Australia in an interview to mark the Oscar-winning film's 50th anniversary: 'I had a crush on Liesl, Charmian, she was so beautiful. God, those wonderful, beautiful blue eyes. 

'I was so much younger than her, I was 13 she was 20, a grown up. I adored her.'

The actor, who went on to star in the Amazing Spiderman 70s CBS series, added: 'I loved all the girls, not the little ones of course.They were all so pretty. But Liesl was something special...

Eyes for someone else: Charmian, then 20, was smitten with her on-screen father, Plummer, then 35, and the pair often shared a few drinks after filming

'I didn't secretly cope with my crush, I told her,' he went on, adding: 'They [Charmian and Plummer] stayed in the same hotel would had a drink or two after work. 

'They didn't have an affair but she sort of implies now she wished they had. He [Plummer] had a string of girlfriends so beautiful you couldn't believe your eyes. 

'He was so good-looking. I couldn't compete with him.'

The actor, who is now 64 and lives with his actress partner Robyn Nevin in Southern Highlands, south of Sydney, reveals he and Charmian share a close friendship today.

Close friends now: Nicholas, who lives with his actress partner Robyn Nevin in Southern Highlands, south of Sydney, reveals he and Charmian (pictured ten years ago) share a close rapport

'We're all really good friends now and Charmian and I have a slightly special relationship now,' he says.

'She is single, was married to a doctor, and has two children. We're all extended families with each other's children..'

In 2010, Charmian joined the rest of the cast, including Dame Julie Andrews, for the movie's 45th anniversary and confessed to the Oprah Winfrey Show how she fell for Plummer during the nine-month film shoot.

Classic: (L-R) Kym Karath (Gretl), Debbie Turner (Marta), Angela Cartwright (Brigitta), Duane Chase (Kurt), Heather Menzies (Louisa), Nicholas Hammond (Friedrich), Charmian Carr (Liesl), Dame Julie (Maria) and Plummer (Captain Von Trapp)

'I had a huge crush on him,' the actress told the chat show host. 'He was so perfect, and he spoke with this perfect British accent.'

Plummer, then 35, was married to his second wife, journalist Patricia Lewis, at the time. He currently lives with his third wife, British dancer and actress Elaine Regina Taylor, in Connecticut. 

Plummer recalled that the drinking sessions, in gaps between shooting, had left him too big for his costume as the stern widower who whistles for his children. 

Oscar-winning: The fairytale classic saw an Austrian family saved by mischievous nun turned governess Maria, (Dame Julie Andrews),  who falls for the very dashing Captain Von Trapp ( Plummer)

The upbeat movie is a tuneful, heart-warming story based on the real life story of the Von Trapp family singers, one of the world's best-known concert groups preceding World War II. 

Julie Andrews plays the role of Maria, the tomboyish postulant at an Austrian abbey who becomes a governess. 

Her wayward ways sees her ejected from the abbey and become a governess in the home of a widowed naval captain with seven children, bringing renewed love and music into the home.

All seven of the grown-up Von Trapp children, Carr (Liesl), Hammond (Friedrich), Heather Menzies (Louisa), Duane Chase (Kurt), Angela Cartwright (Brigitta),Debbie Turner (Marta) and Kym Karath (Gretl) are celebrating the movie's 50th anniversary. 

The Hills Are Alive...The upbeat movie is a tuneful, heart-warming story based on the real life story of the Von Trapp family singers, one of the world's best-known concert groups preceding World War II

The Sound of Music won five Oscars, including best picture, and its soundtrack with songs like My Favorite Things and Climb Every Mountain is one of the best-selling soundtracks of all time.

The picture also received two Golden Globe Awards, for Best Motion Picture and Best Actress, the Directors Guild of America Award for Outstanding Directorial Achievement, and the Writers Guild of America Award for Best Written American Musical.

In 1998, the American Film Institute (AFI) listed The Sound of Music as the fifty-fifth greatest American movie of all time, and the fourth greatest movie musical.

Attention! Widowed naval captain Von Trapp is left to raise his seven children alone until governess Maria waltzes into their lives

Nicholas says he has no regrets filming the classic since it opened doors for him to go on to star in TV classics The Love Boat, Dallas, Dynasty, The Walton and The Brady Bunch, among others.

'I talk to the girls [sound Of Music] or email them all time about life, what we're all going through,' says. 'They've become my sisters and have been since I was 13.'

He added: 'People still recognise me, all of us. I was  on a plane the other day and a woman came up to me and said "I know who you are, you were my favourite in the movie and I had such a crush on you.

'I was never short of friends, female ones, let's just say that.'

Own a piece of the celebration with the 50th Anniversary 2-Disc Blu-ray edition including the all new exclusive documentary The Sound of the City: Julie Andrews Returns to Salzburg.