 Complete the following phrase:  Although he did not reach the final stages of the World Championship in his later career, Charlton continued to perform at a competitive level. His last major achievement was his 109 first round win over Cliff Thorburn at the 1989 World Championship. He qualified for the 1990 and 1991 World Championships but lost in the first round on both occasions. Charltons final appearance at the Crucible came in 1992 where he was defeated 100 by defending champion John Parrott in the first round, the only recorded in the history of the World Championship until 