Thompson founded Madness with Mike Barson and Chris Foreman in 1976, and wrote the group's debut single, "The Prince". Among the other songs, he wrote or co-wrote the singles "Embarrassment", "House of Fun", and "Uncle Sam". His experiences of being a petty criminal and serving time in borstal in his youth inspired his lyrics for "Land of Hope and Glory" and "One's Second Thoughtlessness", the latter an unusual diversion into synthpop for the group. Thompson performed lead vocals for both tracks. He also sang the vocals on his own composition, "Razor Blade Alley", which was a regular inclusion in early Madness shows. Thompson reunited with all seven original Madness members in 1992.