Fairoaks 'tower' is the original one built c1938.
Farnborough had a 'watch office' from c1922 until 1943 when it was replaced by a control tower, but this was found to be inadequate so was replaced 3 years later by another building a few feet away which lasted until 2002 (with a re-modelling-different VCR-in the late '50s), when it was replaced by the present building and the previous 2 were demolished. The original watch office remained in use as a marshallers hut untiil about 1995 when it too was demolished.