When a singer who has been a group’s lead vocalist since its inception, the voice on the group’s biggest hits, leaves for a solo career, who do audiences want to hear — the voice or the group he left behind?

For Ali Campbell — lead vocalist of UB40 from its founding in 1978 until he left in 2008, citing concerns about the band’s financial management — the answer is a no-brainer. Several months after he left UB40, the group chose his older brother, Duncan Campbell, as his replacement.

“If you turned up to see the Rolling Stones, and nobody had said anything, and Derek Jagger came on the stage (instead of Mick), I think you’d be pretty pissed off,” Campbell said during a phone call from Black Barn Vineyards in Hawke’s Bay, New Zealand, where he and two other former UB40 members — Mickey Virtue and Astro — were in the middle of a sold-out tour.

Campbell and his former bandmates are currently in litigation over how and if he can mention UB40 in billing himself.

“I did all the original vocals back in the day, and then Astro did the other ones. What we do is say, ‘We are UB40 Featuring Ali, Astro and Mickey.’ Everyone who comes to see us has seen the posters and heard the radio, and they know who they’re coming to see,” he said. “Whereas those guys just come out as UB40, and so really they’re just trading off the brand name.”

Even so, he adds, “They’re playing pub tours and we’re doing stadiums, and that’s how it is.”

IN SHORT, Campbell’s career hasn’t suffered since he left UB40.

Virtue, the group’s keyboardist for 29 years, left UB40 shortly after he did; they’ve worked together ever since. Hawaii saw Virtue on keyboards when Campbell headlined the 2013 Mayjah Rayjah music festival in Kakaako Waterfront Park, billed as Ali Campbell.

Astro left UB40 in 2013 after 33 years with the group.

Campbell describes the reunion with Astro as “a renaissance.”

“The difference is amazing because now that we’re calling ourselves UB40 Featuring Ali, Mickey and Astro, it means that we can do a lot of the old UB40 favorites that I didn’t want to do when I was out there on my own,” he said. “We can’t wait to bring this show out to Hawaii.”

HAWAII can’t wait, either. The first show sold out so quickly that a second show was added.

“We’ve always had a great time in Hawaii, but I think these shows coming up are going to be extra special — because it’s me and Astro sort of reuniting again, you know, and everywhere we’re playing we’re having great, great shows — and sell-out shows, too,” Campbell said.

“We’re doing the songs that made Astro famous now, added to the set of songs that made me famous, so it’s like UB40 back in the day but with a bit more energy and with more seasoned players.

“The guys I’ve got in the band are all fantastic. We’ve been together eight years now, so we’ve jelled as a band properly. I’d say we’re the hottest reggae band on the road at this moment in time, in the world.”

UB40, named for a British form used to apply for unemployment benefits, was one of the first integrated reggae/pop bands in England. The group formed in 1978, and played its first gig in February 1979. Virtue and Astro joined shortly afterward.

Remakes of “Can’t Help Falling in Love” and “Red Red Wine” topped the Billboard Hot 100 singles chart and were worldwide hits. “Can’t Help Falling in Love” had been a No. 1 hit for Elvis in 1961, but “Red Red Wine” was a relatively obscure Neil Diamond song; Diamond’s own recording of it only reached No. 62 on the Hot 100 in 1968.

UB40’s remake made Diamond a lot of money in composer’s royalties, but they never heard from him.

“It’d be nice if he said hello, but he never has,” Campbell said. “I know that he does a reggae version of ‘Red Red Wine’ now. Maybe we’ll meet him at some point.”

CAMPBELL, Virtue and Astro are now riding the success of their reunion album, “Silhouette,” which was released at the end of 2014. Along with Campbell’s hard-hitting originals on cyberbullying (“Cyber Bully Boys”), war in the Middle East (“Who Will Remember Them?”) and historical revisionism (“History”) are remakes of hits by the Beatles and Bob Dylan.

The title song is the trio’s reworking of the classic “oldie” first recorded by the Rays in 1957 and then unsuccessfully covered by the Diamonds a few weeks later.

The trio’s concert album, “UB40 Greatest Hits Live,” is available at ub40.org. An acoustic album will be released sometime in the spring.

“There’s new stuff in the pipeline,” Campbell says. “We’re collecting lyrics at the moment, Astro and myself, so we’ll be doing something new this year at some point.”