Gervase Spencer was formerly a gentleman's servant. He taught himself to paint miniatures in watercolour, working on the newly fashionable support of ivory. He later also painted miniatures in enamel.

In the 17th century, new techniques of painting enamels allowed delicate portraits resembling tiny oil paintings to be created. These enamel miniatures were first fashionable in continental Europe, but were particularly in vogue in Britain from the 1720s to 1760s. Painted enamels were made by firing finely milled glass which had been coloured with metal oxides onto a metal base, usually gold or copper. The colours had to be applied and fired in several stages, according to the firing temperature required by each colour. Incredible precision was needed for a successful enamel portrait, since each firing carried risks of cracks and bubbles that might ruin the entire effort.

Sir Arthur Gilbert and his wife Rosalinde formed one of the world's great decorative art collections, including silver, mosaics, enamelled portrait miniatures and gold boxes. Arthur Gilbert donated his extraordinary collection to Britain in 1996.