Every month CabbieBlog hopes to show you a little gem of a building that you might have passed without noticing, in the past they have ranged from a modernist car park; a penguin pool; to a Hanoverian gatehouse.

Although the London Zoo’s penguin pool has been featured on Site Unseen close by stands a very rare example of a K3 telephone kiosk introduced in 1929 and repainted in the original colours.

[T]he design of the K2 was accepted following a competition organised in 1924 by the Royal Fine Art Commission. However, it was expensive at £35 14s 0d per kiosk and quite large. For these reasons there was a unofficial policy within the General Post Office to restrict installations of the K2 to London, with a few rare exceptions.

The General Post Office looked to Sir Giles Gilbert Scott to refine the design of his K2 into a more cost-effective solution, manufactured of concrete. At the time concrete was not widely used and the quality of the material varied. The finish of the K3 was fairly crude; concrete did not allow the refined detailing of the K2 to be replicated. K3 kiosks were often damaged whilst in transit for installation as the concrete proved fragile and weathered too easily.

The K3 kiosk is constructed of concrete sections, bolted together, standing on a concrete base. Its general form is a four-sided rectangular box with a domed roof. On three sides of the kiosk, are six rows of three small rectangular panes of glass, with red-painted glazing bars; the equivalent back panel is blank. The door is of teak, with a metal “cup” handle. Above the main body of the kiosk is an entablature, set back from the face of the kiosk, with a rectangular slot containing an illuminated telephone sign, with serif capital lettering on opaque glass.

The roof of the kiosk is domed, formed by shallow segmental pediments with embossed panels. The dome stands on short, cubic capitals, disguising narrow ventilation slots. The K3 does not carry a Royal crown. Unlike the K2, K6 and K8 kiosks, but like the K1 and K5 kiosks, the K3 is not painted red. Apart from the window glazing bars, the external surfaces of the K3 are finished in cream stipple-paint. The detailing of the K3 is simple, without excessive decoration. The execution of the design in concrete is unrefined, the coarse aggregate stone gives the concrete a cruder finish than the General Post Office’s cast-iron kiosks.

Between 1929 and 1935 eleven thousand examples of the K3 were installed, they are now exceptionally rare, today only three remain. Repainted in its original colours this is the only one in London and has been given an English Heritage Grade I listing.