From the Mitcham Youth Handbook of 1949

PHALANX CLUB
Service to their school, the County (Grammar) School for boys, is the qualification for admission to the Phalanx Club, which meets in the County School on Wednesdays at 7.0 p.m. A variety of activities is arranged and the club participates in Youth Council sporting events. All communications should be addressed to the School Captain, County School for Boys, Commonside East, Mitcham.

Source: Local Studies Centre, Morden Library, Civic Centre, Morden.
Reference: L2 (369) MIT