Interesting, OP, that Kirsty was so popular at your school? Are you in Scotland? There was only one in my whole school and it was spelled Kirstie.
I left school in 1989 and my year was a plethora of Kates/Catherines, Rachaels, Sarahs, Nicolas, Clares and Emmas. All with the inevitable Louise/Jane/Elizabeth as a middle name. We had 2 Anne-Maries too.