10th February 2016 | administrator D = Derby Castings The firm of Andrew Handyside was one of the earliest to cast pillar boxes, and went on to hold many GPO contracts; the company went into liquidation around 1930 and a new firm, Derby Castings emerged in 1931. They cast some wall boxes and lamp boxes between 1931 and 1933. The 50 Type D and 75 Type E pillar boxes (large and small oval boxes incorporating a stamp vending machine) were also cast by Derby Castings. Letter Box Study Group 2016-02-10T16:15:51+00:00 The firm of Andrew Handyside was one of the earliest to cast pillar boxes, and went on to hold many GPO contracts; the company went into liquidation around 1930 and a new firm, Derby Castings emerged in 1931. They cast some wall boxes and lamp boxes between 1931 and 1933. The 50 Type D and 75 Type E pillar boxes (large and small oval boxes incorporating a stamp vending machine) were also cast by Derby Castings. https://lbsg.org/testimonials/d-derby-castings/