[4] At the Nelson Mandela 70th birthday open-air festival in 1988, Williamson played alongside Courtney Pine in Wembley Stadium,[5][6] and afterwards was a constant presence at Ronnie Scott's Jazz Club.

He was member of Louis Moholo's Viva La Black (1988)[5] and of Chris McGregor's Brotherhood of Breath (1990).

During the 1990s he led his own band and appeared in projects of Iain Ballamy, Maceo Parker, Bheki Mseleku, US3, and Graham Haynes.

In 1990, Williamson released his first album A Waltz for Grace with Verve,[5] featuring vocalist Abbey Lincoln.

In 1992, he released his second album, Rhyme Time, followed by Journey to Truth in 1994, featuring Cassandra Wilson.