These are GPO (General Post Office) post box keys made by Chubb, London. The General Post Office has a rich history that spans over three centuries. It began in 1660 when Charles II established the GPO to consolidate and control the various postal systems across the country. But in 1969 the era of the GPO came to an end when it was abolished and replaced by the Post Office, a government owned corporation which eventually became what we know today as Royal Mail. The two small pegs at the top of the key were used to open part of the post box.