BLOC Party surprised some of their fans when they returned with the dance-pop of, The Love Within, last year.

And even new bassist Justin Harris admits he was stunned when he heard the group’s ideas for the first time.

“The first track they sent me that they’d been working on was Exes, and I remember hearing it and thinking ‘wow, this is very different to the Bloc Party I know’,” recalls Justin, who’ll play the Barrowland with the group tomorrow night.

“Kele (Okereke, singer) was explaining that with the new material they wanted to write something way more different than they’d written before, they wanted something that was sparse, even comatose.

"I was into that, and then the next track was So Real, which I really liked.”

Both tracks feature on Hymns, a more slow-burning album than some Bloc Party fans might be used to, with gospel and slide guitar now sitting alongside the group’s traditional indie-rock and electronic leanings.

Justin wasn’t actually an official member of the band when work began on Hymns, though.

While 2012’s Four album was an enjoyable, guitar-centric record, the group themselves were falling apart, with some fraught shows taking place.

Drummer Matt Tong departed in 2013, followed by bassist Gordon Moakes two years later.

Instead of ending the band outright, remaining members Kele and guitarist Russell Lissack continued to throw ideas around, and they asked Justin if he wanted to get involved.

He’d previously supported Bloc Party with his other group, the indie band Menomena, and after working together on the songs that became Hymns he joined up full time.

“It certainly made it more appealing to have a creative role, as opposed to just playing parts that had already been written,” says the Portland, Oregon musician.

“Kele and Russell had a very clear vision for what they wanted the record to sound like – I was just coming in and adding my take on those things.

"Although the work that Gordon did in the past was pretty great, too, he’s a fantastic bass player and it’s been fun to learn his parts on the old songs.”

You can tell Justin is still new to the band, though, given that he refers to Bloc Party as “they” and “them” on a few occasions.

The new line-up is completed by drummer Louise Bartle, who at 21 was still in primary school when Bloc Party’s debut Silent Alarm was released.

Justin admits he had a few reservations about such a young addition to the line-up.

“It’s something I was a little bit unsure of,” he admits.

“I hadn’t met Louise until two weeks before our first show together, and she was walking in not sure who I was too.

"She’d played with Kele and Russell before, but this was the first time we’d all played together.

"I knew she was young, only 20 at the time, and I had a little bit of scepticism because of the age.

“But after that first rehearsal I was like, ok, she’s bad-ass.

"She’s a very good drummer and very sharp musically, with a good ear for melody.”

The new line-up has already played more than 20 gigs together, including a one-off gig at the O2 ABC last autumn.

Now they’re on their biggest run of headline dates, topping the bill on the NME Awards Tour alongside Drenge, Rat Boy and Bugzy Malone, and the bassist believes the new line-up has a positive focus on the future.

“Having been in bands for 20 years I know what the tension can be like,” he adds.

“But that currently doesn’t exist with us, and it’s been very positive so far.

"Kele and Russell obviously have a lot of history and work well together – I don’t exactly know what transpired with the original four, but as of now everyone seems quite happy.”

NME Awards Tour, Barrowland, tomorrow, £25, 7pm