The late Queen singer’s composer collaborator Mike Moran once said of him: “Very few people can sing like Freddie Mercury. He’s one of the most unique performers I’ve ever had the fortune to work with. Freddie’s an amazing vocalist and he’s got immense range. Got great control over his voice, great phrasing.” One occasion when Moran was particularly impressed with Freddie’s singing talent was when he collaborated with Montserrat Caballé on smash hit popera track Barcelona back in 1987.

The composer said in the Finding Freddie YouTube documentary series: “I don’t think Fred sung better at any other time in his life. Fred never tried to sing operatically, but Fred was a great performer. He could have done anything really I suppose. The power and the passion he put into it is the same as a tenor in an opera.” However, the amazing duet could have ended up as a “complete disaster”, with the Queen singer having experienced serious doubts that it would work out.

Freddie and Montserrat were originally connected after the Queen frontman revealed she was his favourite Spanish singer during an interview. So afterwards her people made contact wanting the pair to meet up.

Moran remembered: “Fred phoned up and said, ‘I’ve had a phone call from the Caballé organisation and they want me to meet Montserrat and so we’re going on Saturday to the Ritz in Barcelona.’ Fred… was excited for one thing because she was an absolute idol of his “But on the other hand, he said, ‘We might not get on, personally I don’t know what she’s like.’ So we tried to lighten the atmosphere a bit in case it turns out to be a complete disaster. Of course, they got on very well.”

The singers had dinner together at Freddie’s Garden Lodge home in Kensington and after the meal had some time around the piano together singing through various genres of music.

On the occasion, Moran said: “We didn’t need to lighten the atmosphere at all. hey were like old friends after about 10 minutes and that was it. It was received very well, everybody was very surprised. Nobody had any idea that anything like was happening at all.”

Following the meet-up, the opera singer asked if Freddie could write something they could perform together. So Queen frontman and Moran hit the studio and came up with Barcelona. Although, the composer revealed that their two very different singing voices and ranges proved to be quite the challenge.

Moran admitted: “It wasn’t an easy process.” Yet in the end, Barcelona was a great success and Freddie collaborated again with Montserrat the next year with the single The Golden Boy, alongside an entire album together.

Following Freddie’s death in 1991, the song reached No 2 in the UK charts and it featured at the 1992 Olympics in Barcelona. The opera singer herself died in 2018 aged 85 and was hailed as “the best of the best” by King Felipe VI of Spain.