Gilbert was born in Aylesbury, Buckinghamshire, the only son of a successful millwright and engineer, and was educated at what was later described as the "best private school in the county" but which Gilbert himself criticised as "cramming Greek and Latin rather than teaching first principles",[1] At 19 years of age he took over his father's business, and ran it for ten years.

[2] The mill business was quite successful, though limited by lack of capital[2] but a continual struggle against competitors, suppliers and debtors, and he sold his share to his partner and with his ailing wife emigrated to South Australia (perhaps influenced by the high reputation of Australian wheat[1]), arriving in 1869.

After a year of setbacks he secured a temporary position as traveller for Giles & Smith, a large wheat buyer and flour-miller in Waymouth Street, and before the six months' contract was over Gilbert had established a business of his own in North Adelaide.

[1] He was then offered a position with a chaff mill in Tynte Street, North Adelaide, with an option to purchase.

[4] Gilbert was elected to the South Australian House of Assembly seat of Yatala in 1881[5] with David Murray[6] and against William Cavanagh.

[4] He was confined to his room at his Fitzroy Terrace, Medindie,[4] home for many months but retained his faculties to the last and did not take to his bed until the last days of his long and useful life.