Rajaretnam Yogasagarar was the Series 18 champion.
A doctor from Cheshire, commonly referred to on the show as Yoga, made his debut on the first show of Series 18, broadcast on 10 July 1989. In that show, he defeated Monica Kirby 59 – 36, and went on to win five more shows before losing his 7th 44 – 37 to Shirley Scott. Yoga returned for the final rounds as #3 seed, and in the quarter-finals, 'gained his revenge' on Shirley Scott, beating her 46 – 39, and beat octochamp Richard Evans 56 – 46 in the semi-final. In the final against Mandi Hale, Yoga led 82 – 73 going into the crucial conundrum, which he unscrambled in 2 seconds to win the final and the series.
|#||Date||Type||Contestant 1||Score||Contestant 2||Guest||Lex||Max|
|868||10/07/1989||P||Rajaretnam Yogasagarar||59 – 36||Monica Kirby||Richard Stilgoe||Della Thompson||73|
|869||11/07/1989||P||Rajaretnam Yogasagarar||64 – 37||Brian Clarke||Richard Stilgoe||Della Thompson||??|
|870||12/07/1989||P||Rajaretnam Yogasagarar||49 – 37||Margaret Jones||Richard Stilgoe||Della Thompson||69|
|871||13/07/1989||P||Rajaretnam Yogasagarar||58 – 20||Bob Holland||Richard Stilgoe||Della Thompson||83|
|872||15/07/1989||P||Rajaretnam Yogasagarar||47 – 18||Graham Owen||Richard Stilgoe||Della Thompson||73|
|873||17/07/1989||P||Rajaretnam Yogasagarar||56 – 25||Win Strange||Ned Sherrin||Della Thompson||71|
|874||18/07/1989||P||Rajaretnam Yogasagarar||37 – 44||Shirley Scott||Ned Sherrin||Della Thompson||69|
|933||9/10/1989||QF||Shirley Scott||39 – 46||Rajaretnam Yogasagarar||Gyles Brandreth||Catherine Clarke||77|
|936||12/10/1989||SF||Richard Evans||46 – 56||Rajaretnam Yogasagarar||Eve Pollard||Catherine Clarke||72|
|937||13/10/1989||GF||Mandi Hale||73 – 92||Rajaretnam Yogasagarar||Frazer Hines, Eve Pollard||Catherine Clarke||128|
|M60||21/5/90-25/5/90||Masters 2||Richard Evans||96 – 57||Rajaretnam Yogasagarar||N/A||Della Thompson||134|