Mark Ronson is showing me the Woody Allen poster that takes pride of place at the entrance to his recording studio in King's Cross, London. The studio is named after Zelig, the 1983 Allen mockumentary about the fictional character who changes identity according to his environment and appears at key moments in history. Ronson chose it, he says, because growing up partly in New York, with his mother and stepfather - Mick Jones of the soft rock band Foreigner - and partly in London, with his businessman/mogul father Laurence Ronson, he had to "learn how to adapt, to fit in".

You wouldn't associate Ronson with feelings of alienation. He has, after all, produced everyone from Amy Winehouse and Lily Allen to Robbie Williams and Paul McCartney. He isn't doing badly with his own music, either. His recent fourth album, Uptown Special, a collaboration with Jewish-American author Michael Chabon, went to No 1 in the UK, as did his Bruno Mars team-up, Uptown Funk. And at the time of this interview, he is quietly optimistic about his 13th week at No 1 in the States with Uptown Funk, the longest run of any single this decade, and one of only 15 songs to spend more than 12 weeks at pole position in the US.

"I don't want to jinx anything but we [Ronson and Mars] are so far ahead at the top we'll probably get to 13 and if we do then we'll be the biggest [No 1] in five or 10 years. We beat Blurred Lines and Happy already," Ronson says, alluding to the none-more-ubiquitous hits from, respectively, 2013 and 2014 that both featured Pharrell Williams, that other producer turned performer. It's a new phenomenon: the knob-twiddler as star.

"I feel like Pharrell is genuinely a star," he counters. "He sings, and he looks like a rock star. I know he's known more as a producer than someone at the forefront, but he's more of a legit old-school star. With me, ever since my first record, or at least since Valerie [the 2007 version of the song by Liverpool band The Zutons that he produced for Amy Winehouse], people have been going, 'So what does this Mark Ronson guy do?' After I was associated with Lily and Amy, who were both exciting characters, they began to understand what I did.

"It's funny," he continues, laughing at the absurdity of his position as the celebrity obscurity, "but I met this photographer the other day and he told his wife he was taking pictures of me for a Los Angeles newspaper and she said, 'Oh, you mean the white guy in the Bruno Mars video?'!"

He insists the relative anonymity suits him fine.

"It's okay. I don't make records so that people can find out who I am," he says. "I make them because I have a whole bunch of songs in me that I want to record."

Is he the biggest backroom boy in pop?

"I wouldn't say I was the biggest but I'm happy with the backroom, sure," he replies. "Listen, I'm 39, I'm not a pop star age. I can still take the subway in New York and the tube here, it's not like a frenzy. I get recognised, but with a kind of nod. It's not like a selfie catastrophe every time I go out. It's cool. It is a bit of a thrill seeing your name on top of the charts as opposed to in parentheses, but those are superficial kicks."

Breaking chart records in the States is not his only priority. He's just as delighted to have been invited by an organisation called Westminster Young Professionals (whose intention it is to "create a community of central London well-connected young Jewish leaders") for An Evening With Mark Ronson. Next month's fundraiser takes place at Westminster Synagogue in Knightsbridge and will include a conversation with Capital Radio DJ Mark Berry followed by a Q&A with the audience.

I point out the poster for the event that I have on my laptop screen, particularly the bit where he is referred to as a "music legend".

"Woah," he grins, a tad embarrassed, "that's a little hardcore."

How and why did he get involved?

"I've been a member of that synagogue for three or four years - it's where my dad belongs, and the rabbi there performed the service at my wedding [to actress and singer Joséphine de la Baume] and asked if I'd be interested in doing something like that," he explains.

Is he the best-known congregant?

"I'm sure there are people who are powerful in the community - I don't know if there are any other record producers," he says, imagining looking out from the bimah and seeing the famously hirsute, legendary American producer of Neil Diamond and Johnny Cash: "'Ah, there's Rick Rubin!'"

"I like the idea [of this event]," he continues. "It's an easy way to help out, to raise money for the synagogue. I didn't think twice about it."

He might even perform a song or two, maybe with a little help from a nice local Jewish singer - East Finchley's Jess Glynne, perhaps, who the JC interviewed last year. Glynne is also No 1 this week, in the British singles chart with Hold My Hand.

"I wonder," Ronson muses, "if there has been a time in recent history when two Jews have occupied the top spots in both countries? It's a good time for Jews in music."

Not such a good time for Jews per se, at least in the UK. Is Ronson worried about it all?

"I would never change or give a second thought to living life differently to the way I am," he says. "It is troubling, for sure; it's really ugly, and terrible things are going on all over the world right now.

"Our generation has been spoiled," he adds. "We've never had to think about antisemitism living in England, and growing up in New York I certainly didn't have to worry about it. But no, I'm not going to think twice about going to synagogue."

Uptown Special is a veritable J-fest: Ronson, Chabon, even Bruno Mars' father, it turns out, is half-Puerto Rican, half-Jewish on his grandmother's side.

"Everyone has a Jewish grandmother from the Bronx," jokes Ronson.

Just about the only non-Jew on the album was Stevie Wonder, who plays harmonica on a couple of tracks.

"If you'd asked me who was on my wishlist to be on the album, and then said Stevie Wonder would end up actually being on it, I would have said, 'Don't be ridiculous,'" he says. It was one of the most memorable collaborations of his career since, well, Amy Winehouse.

"With Amy, it was like magic," he recalls, wistfully, "because we had this really strong chemistry. We had a good bond, a friendship that made the connection work."

His relationship with his co-producer on Uptown Special, Jeff Bhasker, was a little more strained.

"I kept joking that he's Oscar and I'm Felix," he laughs, a reference to the famous late-'60s movie comedy The Odd Couple starring Jack Lemmon and Walther Matthau. "He's gregarious, stubborn, American, and very verbal about what he thinks is right, and I'm more reserved and English, going about my business. So we had to take a break from each other every now and then."

Whatever, it worked. Ronson agrees that Uptown Special and Uptown Funk have put a decisive end to a fallow period in his career - much like Pharrell, there was a bit of a lull back there for a while.

"It was a lull," he admits. "I was 'cold', in industry parlance. I could see the other producers getting the calls to work on certain projects, and it was like, 'Oh, okay, that's cool… I had a good run, right?' I think when I buckled down to make this record, it wasn't like, 'I'll show them!' but more like a pragmatic feeling of, 'You'd better make the best record you've ever made or no one will give a shit about you for the rest of your life.'"

Job done: by returning to the funk and soul of his youth, Ronson has indeed reaffirmed his status in the marketplace.

"I asked myself, 'What do I do that nobody else does?' I realised that it's the music that runs deepest in me: soul and R&B and all the stuff i used to DJ when I started."

Now, his music is the soundtrack to the spring, and is likely to remain so all summer.

"I was walking down the street yesterday, round the corner from my house, and there's this woman in her mid-30s with [ear]buds on and I can hear [Uptown Funk] coming out of the buds. I've had people send me videos of themselves driving in Morocco or Puerto Rico or Moscow and it's on - it's become one of those songs."

Finally, he has written one of those songs that dominates lives, even permeates the culture.

"I remember when the Russian Police Choir sang Get Lucky [Daft Punk's 2013 single, also featuring Pharrell] at the Olympics. I wasn't jealous, but I did think, 'Wow, imagine having a song so big that the Russian Police Choir sing it!' And now I've got one of those."