By Mark Savage
BBC News entertainment reporter
To mark the annual Ivor Novello awards, the BBC News website is profiling some major songwriters of recent years.
Jam and Lewis have been writing partners for more than 25 years
Jimmy Jam and Terry Lewis have had sixteen US number one singles and worked with artists like The Human League, Sting and Mary J Blige.
Based in Minneapolis for most of their career, they recently moved to Los Angeles, where work has begun on their seventh album with Janet Jackson.
Inspiration can strike in the unlikeliest places - in the bath, sitting on the bus, even queuing for a coffee.
But very few hit songs have been written at the top of Space Mountain.
THE MUSIC OF JAM AND LEWIS
Listen to some of Jam and Lewis' biggest hits - and read what they have to say about them.
That's where Terry Lewis penned the lyrics for one of Alexander O'Neal's hits in the mid-80s.
"It was sort of a deadline situation and he had planned a trip to Disney World," recalls Lewis' co-writer Jimmy Jam. "He called me and he says 'I was on the rollercoaster and I got the lyric!'".
Jam and Lewis have been writing partners for more than 25 years, so they are well aware that ideas can come out of the blue.
Like Prince, Jam and Lewis were part of the Minneapolis scene
"Our creative juices usually get flowing a lot better toward the night time... probably from being musicians from way back and playing in clubs," says Jam.
Jam and Lewis' started their careers playing keyboards and bass in The Time - a funk and soul band whose songs were largely written and produced by Prince.
"The first time we went into a radio station in Detroit the DJ played our single ten times, then he asked people who was playing," says Jam.
"Everybody said 'it's Prince, it's Prince!'"
"I remember being struck that it would be cooler if we had our own sound, and that if we ever got the chance to produce a record we would give everybody their own sound."
It wasn't long before a chance came along - Jam and Lewis were asked to produce a song they had written for the SOS Band, Just Be Good To Me.
During a two-day break from touring with Prince, they flew out to Atlanta to record the single.
But a freak blizzard left the duo stranded in Georgia, and Prince dismissed them from the band.
Jam views working with legends like Earth Wind and Fire "as a fan"
Fortunately Just Be Good To Me was a massive success, and Jam and Lewis soon found their songwriting services in demand.
Jam can recall every keyboard, drum machine and sampler he has used over the years.
He's also got an encyclopaedic knowledge of music - something which helped him win a celebrity edition of Rock'n'Roll Jeopardy in 2001.
It comes in handy in the studio, too.
"A lot of newer artists, when they say 'I want that to sound a certain way', I can usually pinpoint a song or an artist that they should listen to".
Jam is the musical half of the team, while Lewis contributes lyrics - but they are both keen for their clients to get involved.
Jam (l) and Lewis (r) have recently moved to Los Angeles
"We really try to get into their lives, what they want to talk about and what's important to them - then we start crafting songs."
Recently divorced and eager to break free from her family, Janet Jackson was encouraged to put her feelings on track when they joined forces in 1986.
The resulting album, and its title track Control, "turned out to become an anthem for young women who were striking out on their own," says Jam.
The record's strident lyrics were given extra punch by Jam and Lewis' sparse production.
But Jam says "a lot of it was a bunch of mistakes".
"We recorded Control ourselves because we had an engineer who walked out on us. So a lot of things were recorded too loud and were sort of distorted."
"But it made for an interesting sound," he says, "because some of the things [were] fixed and some [were] left distorted.
Usher and Janet Jackson have both recorded with Jam and Lewis
"The record has this kind of loud, frantic sound".
Control certainly made the public sit up and listen. It sold over five million copies and cemented the reputation of its star and its producers.
Jam and Lewis have collaborated with Jackson ever since.
Jimmy Jam puts the duo's longevity down to an ability to bring the best in performers.
"In sports, some coaches are called player coaches - meaning that players really love them because they get along with them," he says, "I think we've always been like that."
"Artists feel like what they're getting is their own."