Squash has its roots in the 19th-century game of rackets, which was popular in London prisons. Around 1830, lads at the Harrow School realized that a perforated ball that "squashed" as it hit the wall added additional variety to the game. The game was quickly picked up by other schools. The early Harrow School courts were hazardous due to their proximity to water pipes, buttresses, chimneys, and ledges.
The ball's preferred substance was natural rubber. Students altered their rackets to have a shorter reach in order to increase their abilities to play in these confined spaces. The school constructed four outside courts in 1864.