Leg spinner

A leg spinner was the type of bowler in the sport of cricket that preferred to apply leg spin. The Fourth Doctor once postulated that a town crier he heard on Ribos was a cricket scout for Somerset, and then noted to Romana I that "they could do with a good leg spinner". He then approximated the wrist movement necessary to apply leg spin to a cricket ball, indicating that it would add considerable spin. (DW: The Ribos Operation)

Behind the scenes
Though Ribos never tells us precisely what "leg spin" is, Tom Baker's hand gestures show us that it involves applying a certain wrist movement prior to the release of the cricket ball. A good leg spinner will be able to make the ball bounce close to the leg stump and then bounce sharply towards the off stump, thereby confusing the batsman