He was the son of Thomas Guest, a partner in the Dowlais Iron Company, and Jemima Revel Phillips.

[1] After attending school, he learned the trade of ironmaking in his father's foundry at the hands of the works manager, John Evans.

Guest was renowned for his ability to roll a bar of steel or cut a tram of coal as well as any of his father's workmen.

[2][4] After his death in 1852, Guest was succeeded by his eldest son, who was elevated to the peerage in 1880 as Baron Wimborne, of Canford Magna in the County of Dorset, on Disraeli's initiative.

Together, they had five sons and five daughters, including: Guest died in 1852 and was buried in an iron coffin under a red granite slab in the local St John's Church, which had been built for him in 1827.