"We all grew up listening to Dennis," says Campbell, who had been delighted when Brown agreed to sing on UB40's next record. "We call it `the Fathers Album', because it will be the elder statesmen of reggae singing our songs, a reversal of the Labour of Love series, which was us tipping our hats to them."
The young UB40 learnt to play their instruments in the late 1970s by ear, listening to records by the reggae greats of the time and copying their moves. Toots Hibbert, Ken Boothe and Burning Spear will all appear on the Fathers Album when it is released next year, but Brown died before he could record a song. "We wanted Dennis, no question," says Campbell, talking by a pool table at the band's studios in Birmingham. "He had a unique sound that everybody tried to copy. You forget how many hits he had, because he had been doing it from about nine years old. He never got the recognition outside reggae that he deserved."
Astro, UB40's toaster and MC, says that no reggae sound-system's set was complete without Brown's seductive singing. "Girls would melt as soon as they heard his voice. Many a relationship was forged on the dance floor to his music."
Brown died in his hometown of Kingston on 1 July, leaving a wife and 13 children. In the 1960s he was a child star, regarded as the island's answer to Little Stevie Wonder, and at 21 he was Bob Marley's favourite singer. The chaotic studio system in Jamaica makes it hard to say exactly, but he is thought to have recorded up to 80 albums for 37 different labels.
Brown had a hit in Britain with "Money in my Pocket" in 1979, but he never quite achieved the crossover success that had been predicted - partly because reggae fell so quickly out of mainstream pop fashion after Marley's death. Nevertheless he remained a huge star on the world reggae scene, frequently headlining the annual Reggae Sunsplash in Jamaica.
The festival was first held in 1979, with Marley the headline act. It has continued to draw fans to Montego Bay every January since, spawning a rival event in the summer.
Capital Radio sponsored the first London Sunsplash at Selhurst Park in 1984, but the event outgrew itself fast. A quarter of a million people were at Clapham Common in 1987, helping Maxi Priest and Freddie McGregor celebrate 25 years of Jamaican independence and the centenary of Marcus Garvey's birth.
"It was the biggest event in Britain that year," says the veteran promoter Junior Lincoln. "There was no trouble, the police report on the event made me very proud, but it was difficult to get a regular outdoor venue for an event of that size. People were wary of us. We tried for three or four years, then we had to give up."
Sunsplash returns today with a licence for 50,000 people. The bill reflects the influence reggae has had on a wide range of modern musical styles - with Wyclef Jean and Asian Dub Foundation appearing alongside roots performers like Isaacs.
"Sunsplash is a multicultural, multiracial festival that caters for all ages," says Lincoln, who promises an artificial beach created with five tons of sand and 40 palm trees. Children under 12 will get in free, but parents have been warned not to bring them younger than five because of the "extensive sound levels".
Sunsplash: Victoria Park, E3 (0171 490 3705), from noon today