[3] He was born in London to the Australian banker and politician John Lamb and Emma (née Robinson).

His mother Emma Lamb (née Robinson) was the daughter of the deputy chairman of Lloyds Bank.

His family migrated to Sydney in 1829, and, after his education, Lamb became a clerk in his father's mercantile firm and became a partner in 1847.

In January 1855 Lamb had become an original shareholder and director of the Colonial Sugar Refining Company and in 1880 chairman.

His brother John de Villiers Lamb married Henrietta Octavia (née Smith), sister of Thomas Whistler Smith, an Australian politician and banker who became deputy chairman of the Commercial Banking Company of Sydney, and who was in turn the brother-in-law of John Street, founder of the Street dynasty.