Brighton's Mike Rosenberg spent his 27th birthday in a Glasgow Travelodge, having just busked to 16 people in the rain.

“I was getting frustrated,” admits the songwriter behind Passenger three years on, calling while on tour from “a small random town in Switzerland”.

“I had been playing music for so long, working so hard, writing new songs, doing everything I could to break through. I was thinking: ‘What am I doing?’ and wrote a song to cheer myself up.”

The finished song, 27, was released last month. As well as counting down what he had already achieved in his life – from eight years’ sleeping to smoking 87,000 cigarettes – 27 is almost a manifesto for his life as a songwriter, particularly the lines: “I write songs that come from the heart/I don[‘t give a f*** if they get into the chart”.

“This song means a lot more now than it ever has done,” says Rosenberg. “It reminds me why I do it still, and not to get carried away with whether I’m on the BBC Radio 1 playlist or not.

“What I care about is whether people connect with my music and records. Maybe when I’m 37 I’ll do another updated version.”

Let Her Go In the time in between writing 27, and its eventual release on Whispers earlier this year, a lot has changed in Rosenberg’s world – largely because of another song.

Let Her Go became an international hit on its release in 2012 – the second single to come from Rosenberg’s fifth Passenger album All The Little Lights, which he recorded using the funds he earned from busking around the world. So the story goes the song was originally picked up by Dutch radio, breaking the top 40 in December 2012. From there it went on to top the charts in Australia, Austria, Belgium, the Czech Republic, Denmark, Finland, Germany, Greece, Ireland, Italy, Luxembourg, Mexico, New Zealand, Norway, Sweden and Switzerland, as well as reaching number two in the UK singles charts and breaking the Billboard top five in the US.

It was the beginning of two years of constant touring around the world for Rosenberg – which hasn’t really stopped.

“Let Her Go is quite old now, but in Europe the venues are still getting bigger and more people are going to shows,” says Rosenberg.

“What makes me so happy is that now all the hype from that song has died down people are still coming out to see me.”

All The Little Lights All The Little Lights followed the single in becoming an international hit – earning platinum status in the UK for selling more than 300,000 copies.

The pressure was on for the follow-up – and Rosenberg admits he’s very happy how his June release Whispers came out.

“I remember thinking there were two ways of looking at it,” he says. “I could either say: “I’ve had a hit single, now I need to have five more. I need to make the album bigger and better.”

“Or I could go in and think: “It’s great I’ve had a hit single – if it happens again in my career then brilliant! If not I’ve got a great story for my grandchildren.’ “I think this is the best record I have made as far as the group of songs, production and performance. It’s not going to sell as many as All The Little Lights, but I’m very proud of it artistically and creatively.”

Rosenberg puts part of the reason for the high quality of the album down to the long gap between his last two releases.

“Over the previous three years I had released an album every year as I write a lot of music,” he says. “Because of the success of Let Her Go I wasn’t able to do that. It meant every song that got on Whispers had to work for its place – hopefully there aren’t any fillers on there. The songs date back from three years old to much more recent ones.”

There is a much more upbeat tone to the album too – although sometimes as with live favourite Bullets it can be in contrast to the story being told in the lyrics.

“Being upbeat wasn’t really a consideration with the album,” says Rosenberg. “You have to be careful not to have too much of the same thing the whole time.

“Singer-songwriter music can get very bloody serious. As a songwriter you want to get a whole bunch of different emotions onto the record so it’s not just about melancholy, regret and moans about how ridiculous things are. I try to cover everything as a writer – 27 and Scare Away The Dark [Rosenberg’s attack on a world obsessed with computer screens] probably help that upbeat feel.”

Busking Many of the songs had been played live over the last few years – helping Rosenberg choose some of the tracks.

“Busking was so good for trying out new songs,” he says. “There was no pressure – you could walk them out and see what happened.

“It was a great system for songs to go through.”

Having built a career through busking around the world following the break-up of the original Passenger band in 2009, Rosenberg still busks on occasion, although he doesn’t sell CDs on the streets or put out his guitar case for change any more.

“For the earlier part of the year I did lots of busking in the US, Australia and UK,” says Rosenberg, who played an impromptu show on Brighton seafront in May.

“It’s something I love to do – back in the day it was what kept body and soul together and allowed me to fund my other albums.

“Now it’s for people who can’t come to the gigs – it’s a fun thing to give back and say thank you. Everyone is still so respectful – they just come and listen. I was worried it might not be possible if I got to a certain level, but I’m blown away by what a nice bunch of people my fans are.”

On stage he has retained that busking style – rejecting the idea of taking a band on the road with him to recreate the arrangements on Whispers.

“I thought long and hard about putting a band together at the start of the year,” says Rosenberg, who headed up a five-piece band under the Passenger monicker between 2003 and 2009 which included fellow songwriter Andrew Phillips and Marcus O’Dair, who now both work together as Grasscut.

“I was close to doing it, but then I pulled back. I realised I’d been playing on my own for five years and I had got good at it. It would have been a rash move to go from that into a big live band set-up.

“I think I will play with a band at some stage in my career, but right now the solo thing really works. It’s intimate and really direct – there’s a great interaction between me and the crowd.

“Putting a band together would dilute the intensity around that.”

He admits busking has taught him a lot when it comes to playing live.

“When you start busking you have to engage people,” he says. “You have to come up with clever ways of drawing people in – and I think that comes into the live show.

“Part of the reason why the show works is there is a lot of story-telling, jokes and silliness – if you didn’t then the guitar and vocal would get a little samey. I try to make it as interactive as possible, and make people feel as comfortable as possible.”

Inspiration He has also taken inspiration from a fellow UK artist whose ascent to stardom was even more dizzying. Rosenberg supported Ed Sheeran on tour numerous times – including an appearance at the Brighton Centre last year.

“If I hadn’t been with Ed that year before it all kicked off for me I wouldn’t have been able to keep up with it,” admits Rosenberg. “One of the many amazing things about Ed is how calm he is about everything. He is open and generous with people – how he approaches things was really inspiring to see.

“He’s quite courageous and a lot of that rubbed off on me – he gave me energy to give it a go when I’d become so gutted about busking for so long.

“Watching Ed gave me encouragement and support – it was fundamental to me believing in myself, to be able to pick it up and run with it.

“The main thing I came away with was to remember the fans – it’s really bloody important how you treat them. Ed is 23 now, but he’s got a much wiser head than I have.”

Rosenberg is trying to pay the experience forward, taking Australian singer-songwriter Stu Larsen on tour with him.

“It works like a musical apprenticeship,” says Rosenberg. “I’ve been touring with Stu and produced his next record, which is exactly what Ed did for me and people like Snow Patrol and Example did for Ed.”

The rewards have kept coming for Let Her Go – with Rosenberg being presented with an Ivor Novello award for the Most Performed Work in May. The award ceremony counts among his most starry events this year.

“Jimmy Page was on the next table to me,” he remembers. “There were two members of Fleetwood Mac too. I did think: ‘What am I doing here?’ “It’s funny how quickly you become accustomed to it. You realise that famous people are no different from anybody else. They are still human beings if you approach them in a normal way. I had a really nice chat with Sam Smith.

“His songs are great, and he has an amazing voice. He seems down to earth and grateful – I’m happy to see things working out for him.”

Rosenberg’s parents still live in Shoreham and he keeps in touch with many old schoolfriends based in the city.

He admits playing Brighton is a show he looks forward to and gets nervous about.

“I think I played every single pub in Brighton at one stage or another,” he says. “I have some memories of great gigs, and some slightly sadder ones where I would be playing my hometown to 20 people. It’s going to be great going back to play two shows at the Dome – I’ve never played there before.

“Usually when I play two nights in a row at one place the gigs are really different. The sound and the crowds can completely change – people have a few more beers on a Saturday, whereas on a Sunday they have work the next day. The roomful of people changes from night to night.

“I’ve played Central Park in New York and Sydney Opera House, but Brighton is always the most important gig for me.

“It’s the most nerve-wracking one.”