Cardboard box labelled GKN Nettlefolds Parker Kalon, with illustrations of security screws. Base and lid. Box stapled together with metal staples.

Parker-Kalon was a successful USA steel company that developed the first sheet metal tapping screw and it appears that GKN sold their screws under licence in the U.K. from 1940 onwards.There are adverts in Scottish newspapers also selling Parker-Kalon screws but the difference with GKN is that theirs were co-branded as GKN PARKER-KALON.

The castle branding was used by GKN after the Nettlefold's merger and represented the Castle Iron Works at Rogerstone where John Nettlefold worked in 1890-1 and this was also known as the Dowlais works. The castle branding appears on a box of cricket spikes in the MCC museum dated 1900 and so it seems this element of the brand was use since then.

A couple of other points of interest from going through local papers were that the Nettlefold name was resurrected by GKN as in 1948 these screws were referred to as NPK (Nettlefold Parker-Kalon) screws also in 1941 Parker-Kalon of New York made donations in the U.K. to the war effort via GKN which indicates a strong partnership between the 2 companies.