Backward square leg

Backward square leg was a fielding position in cricket. According to the Fifth Doctor, Graham Dilley was playing deep backwards square leg during the final stages of the 1981 Ashes series. (PROSE: Graham Dilley Saves the World)

Behind the scenes
Dilley gives no indication what "deep backward square leg" might possibly mean beyond being a fielding position. In reality, "backward square leg" is behind square leg. It is more or less parallel with the top of the crease on the bowler's left as he approaches the pitch, right on the border between the outfield and the infield, at about a 45-degree angle to the batsman. In other words, the position has an awful lot of commonality with that of in baseball. A deep backward square leg is simply one that's firmly crossed into the outfield.