Dyer had joined the Royal Horse Artillery in 1916 and was promoted to Gunner-fitter, then Sergeant Instructor Armourer where he began working with copper, creating 'trench art'. After service in France, Belgium and Egypt, he returned to Cumbria in 1922, then walked South to find work, setting up a workshop behind a forge in Mousehole.  Working in Mousehole during the 1920s, he was strongly influenced by the Newlyn School of craftsmen near Penzance.

He began by making items to suit local demand. Unable to interest Tom BATTEN and Johnny Payne COTTON in handling his output at Newlyn Copper, he continued to work independently for about ten years. His best pieces show superb craftsmanship, often making use of familiar 'Newlyn' motifs of birds, shells and sea-weed. Other pieces have finely drawn local views such as St Michael's Mount.

By 1930, however, competition from cheap foreign imports forced him to close his business. The three pieces shown at the 1986 Exhibition of Arts and Crafts in Newlyn were a cylindrical tea caddy (impressed 'H Dyer', inscribed 'St Ives'), an ash tray, and a chamber candlestick.

2019: A recent correspondent, whose grandfather and Herbert Dyer were close friends, casts doubt on the paragraph above regarding the closure of Dyer's business. The correspondent remembers (and his Mother has confirmed) that Dyer was still making pieces in the 1960s, mainly as wedding gifts, from his functioning workshop. The correspondent feels privileged to be currently renting these premises as a stained glass workshop.