Benjamin's brother Andrew apprenticed under Dr Arnoldi and was one of the founders of the Montreal Medical Institute, the forerunner to the McGill School of Medicine.

Holmes began work as a clerk with a group of Montreal merchants under Horatio Gates, but joined the Canadian Light Dragoons during the War of 1812, becoming lieutenant in 1813.

However, after his first term as a member of the Legislative Assembly of the Province of Canada, he found his political neutrality called into question by the English-speaking business community.

[1][2] Holmes then began a merchandise and railway promotion business with John Young, a fellow merchant and politician in Montreal.

[2] He then became involved in the construction of a railway to connect Montreal to the ice-free port of Portland, Maine, and became a vice-president of the St. Lawrence and Atlantic Railroad.

had taken his seat in Parliament with prejudice for his guide — the veil had since fallen from his eyes, and he was ready to act cordially with gentlemen of French origin.

However, over the course of the three annual sessions of the Parliament, Holmes gradually shifted towards the coalition of Reformers and the French-Canadian Group, and away from supporting the governor general.

The major showdown between Governor General Sir Charles Metcalfe and the Reform ministry of Louis-Hippolyte LaFontaine and Robert Baldwin came in 1843, over the implementation of responsible government.

Holmes was one of the co-sponsors of a resolution in the Legislative Assembly, supporting the outgoing Reform ministry and calling on the Governor General to respect the principle of responsible government.

[9][10] Holmes returned to work at the bank, but he found that his political stances hampered his reputation for impartiality in the business community.

He was disappointed at not being named to the Cabinet, but supported the Lafontaine-Baldwin ministry in the Assembly, including the debates over the Rebellion Losses Bill.

In 1843, Holmes was involved in unsuccessful mediation efforts to avert strikes by workers on the Lachine and Beauharnois Canals, the bloodiest in the history of the Canadian labour movement.

In a late recognition of his contribution to the Reform cause, the Liberal government of John Sandfield Macdonald and Antoine-Aimé Dorion appointed Holmes as the receiver of customs at Montreal in 1863.