A- 88 ways, according to research carried out in 1999 by Dr. Thomas Fink and Dr. Yong Mao of Cambridge University. The two physicists applied "knot theory," normally used in physics and the study of DNA, to calculate the figure. They applied a limit of nine moves of the wider end of the garment to the right, left or centre and away or towards the shirt. However only 13 possibilities were considered aesthetically acceptable, of which 4 - the Saxon or Pratt knot, Windsor, Half-Windsor and Four-in-hand- are widely used already. Dr. Fink admits that all 13 are simply fatter or thinner versions of the same V-shaped knot.