Eastcote also housed an outstation of the Bletchley Park codebreaking activities during the Second World War, with several codebreaking computers in use. This operation became the precursor to GCHQ, which remained in Eastcote after the war until the department moved to purpose-built buildings in Cheltenham in 1952.
Eastcote was originally recorded as Ascot, one of the three medieval tithings of the parish of Ruislip, along with Westcot and Norwood. Norwood, in the north of the parish, became Northwood; Westcot, in the west became Westcote (the main Ruislip village), and Ascot, in the east, became what is now Eastcote.
