Hi,
Could Cecil have been born abroad, his father in the services?
On the Consular Birth Indices there is a
Cecil Cobb born Port Said, Egypt between 1916 and 1920, mmn not given before 1966 and no specific year though there is a reference number.
On freebmd you can see two births and there is a large gap between them, perhaps Cecil fits in there.
Did find a Harry James Cobb, on board ship abroad in 1911.
Cathy

modified, sorry Harry James(no Geoffrey), also another possible in the Army in india.If you think this may be Cecil there is a marriage and passenger list, born 25/06/1918