Click on any photo to see a larger version...
This is the Mettoy Railways No.5623 Accessory Set which comprises three items, a Single Arm Signal with Lattice Type Frame, a Signal Box and a Tunnel. The set is designed for use with 'O' gauge railway items and, being British made, this would equate to approximately 1:43 scale as used in Europe and the UK, rather than the 1:48 scale more commonly used in the USA. [For a more comprehensive discussion on the whys and where-fors regarding scale and gauge refer to Wikipedia's O scale article HERE.]
Mettoy also made O gauge train sets during the 1950-60s period when this item was produced.