Holbrook came to Victoria, British Columbia at the start of the Fraser Canyon Gold Rush of 1858.
He settled in New Westminster the following year when it became the capital of the Colony of British Columbia, opening a store there.
Holbrook opposed the union of the colonies of Vancouver Island and British Columbia in 1866, which led to Victoria becoming the capital.
In 1871, he was named Chief Commissioner of Land and Works in the provincial cabinet; he then became president of the Executive Council instead.
In 1884, he published British Columbia gold mines; a paper read before the Liverpool Geological Association ....