Nicknamed the Vermillion Giant, the K4 was the combined telephone and post box. An unsuccessful design, only 50 were ever produced. Here are most of the known survivors.

Amberley Museum and Heritage Centre, West Sussex
Severn Valley Railway, Bewdley, Worcestershire (original location)
Bolton Street Station, Bury
Frodsham, Cheshire

Whitley Bay, Tyne & Wear
East Somerset Railway, Cranmoor, Somerset
Sand-Le-Mere Camp Site, Tunstall, Yorkshire

Unknown location
Warrington, Cheshire
Bewdley, Severn Valley Railway, 2011