On the streets of Paris, revolution is in the air. The people want to take back control from an out of touch government whose leaders are shoring up their own wealth. Barricades look set to be leapt. Such is the way of history repeating itself in France, from the 19th century uprising through to 1968 and even the current, and slightly more ideologically ambiguous wave of street protests by the so-called Gilets Jaunes – the yellow vests. It was seeing photographs of the latter in a French newspaper that struck a chord with Claude-Michel Schonberg.

“Those pictures looked exactly like the set of Les Miserables,” says the composer of one of the most iconic pieces of musical theatre in the late twentieth and early twenty-first centuries.

“First of all it made me realise that Les Miserables is still relevant. Secondly, it also made me realise that in 200 years we have learnt nothing.”

Maybe this is why the current year-long UK tour of Les Miserables, originally adapted by Schonberg and writer Alan Boublil from Victor Hugo’s 1862 novel, has pretty much sold out already.

Arriving in Edinburgh this month for the first time in 20 years for a month-long run, the English-language version of Boublil and Schonberg’s show has been a fixture of the London theatre circuit since Trevor Nunn directed a co-production between the Royal Shakespeare Company and Cameron Mackintosh at the Barbican in 1985.

This makes it the second longest-running musical in the world.

Despite the success of putting Hugo’s story charting ex-convict Jean Valjean’s travails through poverty-stricken France onstage, Schonberg for one isn’t quite sure of the reasons why it happened.

“It’s a phenomenon I don’t really understand,” the now 74-year old composer admits of a creation which introduced the world to songs now regarded as modern classics such as I Dreamed A Dream, “but the show is more popular than ever. I must say, I’m totally surprised.”

By the time Les Miserables opens at the Festival Theatre in Edinburgh, the new six-part TV adaptation of Hugo’s book scripted by Andrew Davies will be mid-way through its own run. With Dominic West playing Valjean as part of a cast that includes Olivia Coleman and David Oyelowo, rather than claiming kin with Boublil and Schonberg’s take on things, advance publicity appears to pointing up the fact that it is categorically not the musical, and shouldn’t be confused as such. Viewers and critics have already criticised this sans songs version as being flat.

With Les Mis the musical itself filmed in 2012 with Hugh Jackman as Valjean, this too is something Schonberg doesn’t understand.

“Whenever I read an article about the BBC version, they are saying it is the real version of the novel and not the trivial musical stage version,” he says.

“I don’t know how you can promote something against it. People know the title because of the musical show, but each time there’s an adaptation, they all make the point that they are not going to have anyone singing. But who knows? This one might be very good. I will look at it carefully.”

Schonberg probably doesn’t need to worry too much. As he points out, there has been more than 50 films based on Hugo’s novel, with over 20 TV adaptations as well as another 20 different versions onstage. This is how great stories work as they are reimagined for every age. Indeed, it was another musical adaptation of a nineteenth century novel that was the starting point for Les Miserables.

“Alain saw Oliver! in London,” says Schonberg, who had previously collaborated with Boublil on La Revolution Francaise, France’s first rock opera, produced in 1973. “I said to Alain, next time we find a big subject, we have it as a sung-through musical, and when Alain saw Oliver!, that gave us an idea about how to do it.”

Lionel Bart’s musical version of Charles Dickens’ novel, Oliver Twist, had already been adapted for film by Carol Reed in 1968 by then, after being first seen on the West End eight years earlier. Prior to putting Les Miserables onstage, as was the fashion then, Boublil and Schonberg released a recording of it as a concept album. This approach had already paid dividends for the English musical theatre team of Tim Rice and Andrew Lloyd Webber with Jesus Christ Superstar and Evita, and Schonberg had already scored hit records in France.

Three years after the Les Miserables concept album had led to the show’s original French production, it was heard by British producer Cameron Mackintosh after it was passed on to him by director Peter Farago.

“Two years after the show closed in Paris, Cameron was organising his records and put it on,” Schonberg recalls. “and after that we heard he was looking for those crazy French guys, Schonberg and Boublil”

While the pair worked on new drafts of Les Miserables, Mackintosh was riding high on the success of Cats, directed by Trevor Nunn, who had also overseen David Edgar’s epic staging of Dickens’ Nicholas Nickleby, and knew how to put on a big show. Success was far from guaranteed, however, and the opening night of Les Mis was a critical disaster.

“The critics were very bad,’ says Schonberg, actually using the v word eight times. “Cameron has a tradition of having a lunch the day after an opening night, and it was like a funeral. We thought it was finished, and during the lunch Cameron kept trying to call the box office to measure the scale of the disaster, but couldn’t get through. Eventually he received a message to say that the reason he couldn’t get through was that the show had sold 5,000 tickets, and in two weeks would be sold out.”

Les Miserables went on to win an Olivier Award for the most popular show, while on Broadway it won three Tony awards.

The current touring version is directed by Laurence Connor and James Powell for a production reinvigorated for the show’s 25th anniversary in 2009. The result is a very 21st century Les Mis, which utilises projections based on paintings by Hugo created by son et lumiere auteurs Fifty-Nine Productions. The internationally renowned team led by Leo Warner and Mark Grimmer, who have come a long way since their early work at the Traverse Theatre, the National Theatre of Scotland and with Stellar Quines Theatre Company.

Having worked worldwide on the National Theatre’s production of War Horse and the 2012 Olympics, more recently 59 have been responsible for opening events of the Edinburgh International Festival, Deep Time, Bloom and the First World war-themed Five Telegrams. The latter projected images onto the walls of the Usher Hall accompanied by a thundering score by Anna Meredith.

“There have been so many improvements to Les Miserable this year,’ says Schonberg. “That has a lot to do with technological developments which wouldn’t have been possible even five years ago.”

This keeps the show fresh for several generations of theatre-goers, as was proven last week, when Schonberg met a woman who told him how she’d seen Les Miserables a staggering 300 times.

“For Christmas she was taking her children and grand-children to see the show with hr again,’ he says.”

What Les Miserables taps into, again, Schonberg isn’t sure about. All he can say is that “I think we did the right job, but it is the novel that is responsible for the success of the show, and for whatever reason, people seem to leave the theatre a bit different. People are scared for the future. They’re all looking for a bright tomorrow and waiting for the sun to shine, and people come out of the show perhaps believing they can be a better person.”

Les Miserables, Festival Theatre, Edinburgh, January 22-February 16.