He succeeded his father as owner of the Bazaar and was also chairman of the West Middlesex Waterworks Company, a director of the London Life Association and of the Westminster Electric Supply Corporation.[2][3]
The Local Government Act 1888 created a new London County Council, with the first elections held in January 1889. Boulnois was chosen by the Marylebone Constitutional Union to contest the electoral division of Marylebone West.[10] He was elected as a member of the Conservative-backed Moderate Party, which formed the opposition group on the council.[2]
He visited Egypt in early 1901,[13] and again in late 1902 for the opening of the Aswan Dam.[14]
Boulnois maintained two residences: a town house in London's Portman Square and "Scotland", Farnham Royal, Buckinghamshire.[2][4][5] He died at his Buckinghamshire home in May 1911, aged 72.[2]