It consisted of the main settlements of Coulsdon and Purley, both in the parish of Coulsdon, along with the parish of Sanderstead and (from 1933) Farleigh.
Eventually the LB&SCR gained Parliamentary approval to build its own independent line between Coulsdon North and Earlswood which bypassed the SER stations of Coulsdon South, Merstham and Redhill.
Coulsdon College was formerly Purley College and that was formed from Purley High School for Boys and Purley High School for Girls.