London Cannon Street
This is a Southern Railway platform ticket for London Cannon Street station. Sadly it has no date, but the Southern Railway was nationalised into British Railways from the beginning of 1948. The (No.3) refers to the ticket window it was issued from. The ticket also has a circular clip at the number 7 which might relate to the original time someone bought the ticket, or might be a coincidence.
Cannon Street survived intact until World War 2 but then suffered 20 years of destruction at the hands of the bombs and corrupt developers. It lost its glass, then its roof, then its frontage building. Now the landmark twin towers survive on the north bank of the Thames and it has offices topped by an exclusive garden above its platforms. Read more here.