British composer, arranger, record producer and multi-instrumentalist Simon Franglen has worked with some of the biggest names in pop music — from Michael Jackson to Madonna — but it is his work on blockbuster soundtracks, namely Titanic and Avatar, that has brought some of his greatest chart successes.

Franglen's involvement on those came as a result of his longstanding collaboration with Oscar-winning composer James Horner. Their latest, and final, project together is the score for Antoine Fuqua's remake of The Magnificent Seven. The work had just begun, with Horner developing some base themes, shortly before he died in a plane crash. Rather than outsourcing the job to another composing team, the film's director turned to Franglen to finish Horner's final opus.

Ahead of the film's opening at the 2016 Toronto International Film Festival, CBC Music spoke to Franglen about his friend, taking on a challenging score under even more challenging circumstances, and the importance of getting it all right.

Can you talk about the first time you met James Horner?

He asked me to come work with him on Titanic because I had a skill set that included the way I used synthesizers at the time — it was somewhat different than most people. He had a longtime collaborator, Ian Underwood, who is one of the heroes of film music as far as I'm concerned, who had been his synthesist. I feel I brought in a slightly different feel — coming from pop music, it had a record-based edge to it.

We set up at a small studio in the valley in Los Angeles with the three of us stuffed in to a room — Ian, and James in the middle, and me on one side amongst racks and racks of synthesizers. Jim Cameron would come and squeeze in. Part of the problem was they had no money — remember Titanic was the film that was going to bring down two film studios. So we had to do things using synthesizers and samples because we had not enough money for an orchestra through the whole film.

The next time was when he asked me to come see five minutes of another film ... which was Avatar. I looked at that and decided it was going to change the world and I ought to be involved. And from that point on we just worked very closely. In recent years I became his score producer and arranger and that was an evolution that happened because we had a really good working relationship and became really close friends. We had a great team as well. Teams are underrated in music and I think in this case there was an incredible set of people who enjoyed each others' company and James was crucial to that.

The team dynamic is interesting. What was the working process like?

There are a number of films when I'd get brought on as an arranger, with other composers. Part of that is to bring in my skill set, in terms of my character ... but also to enhance what they have. Being a composer is being the pointy end of the stick. The politics and the dynamic of working with the director and producers is really tough, and the music is often much simpler than the rest of the process of making a film.

Take something like Avatar. I had a free hand with everything that was non-orchestral. James allowed me to create the sounds and textures of [the film's fictional planet] Pandora. He was writing this exclusive music and I was able to provide some colour. It doesn't diminish what a composer does in any way. The way the scores have evolved in terms of schedules and the constriction of time, you really need a team to sort of bring the whole thing together.

How did work begin on The Magnificent Seven?

[James] was in London and we met up because he wanted to write some themes down quickly with me and Simon Rhodes, an arranger and his longtime engineer. So we spent a week. Part of that was because there was an enormous schedule coming up for us. We had The Great Wall, the Matt Damon film, Hatchet Ridge, the Mel Gibson film ... a number of major projects coming up that were all due. He wanted to get a jump on themes to Antoine Fuqua, so he'd get some feedback. We laid down these themes and then flew back to Los Angeles.

I spoke to him the day before he died. The next morning everything changed. I switched my phone on and this stream of messages came — this horrendous thing happened. He was really in a great place, really looking forward to The Magnificent Seven.

What did you do next?

I was talking to ... the team and I didn't want to let these themes sit there and do nothing. So what we agreed was that Simon Rhodes and I would arrange a suite of music, which we did. I hired an orchestra, and then two weeks later I flew to Louisiana, and told Antoine I had a gift for him. I gave him a CD that was the themes, and said this is a gift from James. I knew Antoine from Southpaw, and he said: I want you to finish this, to take this score on. We talked to MGM and they signed off on this, which is a very gutsy move by everybody involved. Then over the next nine months the score evolved.

You've embedded a Horner signature sound into the score here. Can you explain?

We put it in there once. We had to. That's the "Danger Motif" ... one of the most spoken about things in film music. It was the right thing to do. It isn't meant to be anything other than being the right thing in that moment for the score. We aren't trying to create a mausoleum to James's heritage. This is a living, breathing score that needed to reflect the film it was in. And needed to reflect Antoine's movie.

Was there an intent to pay homage to the Elmer Bernstein score from the original film?

Yeah. We put Elmer in the film. We have nodded to the master. When James and I were talking about this, his one worry was this was a poison chalice. How do you take over scoring a film called The Magnificent Seven when [it] is one of the most iconic film scores of all time? That was a big issue for him. As we said to him at the time: if you don't do it, think of who might?

The problem was it felt anachronistic in the body of the movie. Movies as they are now — they are louder, grittier and more intense in every regard. As the film has evolved, so has the evolution of film scoring and arrangement.

So ... there wasn't anywhere where it felt right. We found a place for it, and I think it is the appropriate place, and the solution we've come up with probably reflects the same problem they had with [updating] Star Trek. When you put it in the middle of the film, it snaps people out of the film. Either it didn't feel right, or you were immediately remembering Yul Brynner. This is a completely different story, a completely different style. The score has to reflect that.

Elmer is one of my favourite composers, if you take everything he's written throughout the years ... this huge diaspora of work. James felt the same way; Elmer Bernstein was one of his favourite composers. Our solution of making sure we pay homage to Elmer is good. We've taken the heritage of cowboy music and remembered it.

So the score has a lot of elements. What comes to mind when you consider it as a whole now?

I hope it has swagger. These guys are mad, bad and dangerous to know. We used a lot of different colours. Part of that came from Antoine, who was referring to things like [Horner's score for] Thunderheart, with woodwind. The banjo was a sound I was quite proud of. It took me almost a week to get that particular texture with the banjos going. Which is this repetitive motif, which is slightly out of time, out of tune. Meant to be like fingernails on the blackboard. Then there is this string line ... that winds its way around the banjo. The idea was to have not much else going on just to make it really just nasty. We used instruments from Mongolia, we used humming, voices ... I didn't want to use very many synths — this is a 19th-century film — but you need to have that groove that we all love from contemporary scores. Part of that was to use natural instruments, guitars and percussion. But then we have the cinemascope of an 80-piece orchestra.

Was there ever any hesitation in your mind about taking this one on?

I spent years working with James. It was natural as breathing. It was a labour of love. Everyone came from the same point of this view, which is that they wanted to find a way of honouring James and his enormous legacy of film music, in terms of what he brought to the art. But also that we wanted to say goodbye to him for a project that he was really looking forward to. The Magnificent Seven was something we had really urged to Antoine to take forward.

I hope James looks down and is pleased with it, and that it reflects his spirit. The orchestra really gave of themselves. The way we put it together, it was an experience that everybody will remember. We're very proud of the score.