One of his sons from his first marriage, Alexander Roberts Dunn, entered the British Army and became the first Canadian to earn the Victoria Cross.

As time went on, the province began to borrow heavily to cover its public works plans, improving roads and canals.

Dunn had the primary responsibility for raising the loans, at first locally, and then increasingly on the British financial markets.

[1] Increasing concerns about Dunn's financial dealings, both in the Colonial Office and in Upper Canada, eventually led the Lieutenant Governor of Upper Canada, Sir George Arthur, to appoint a committee of investigation, composed of members of the Legislative Assembly.

There was no evidence that Dunn had dealt improperly with the public funds, but he took any criticism of his financial administration as an attack on his personal integrity.

Arthur advised the new Governor General, Charles Thomson (later Lord Sydenham) that Dunn was a “weak man, influenced by the impulse of the moment, and wayward to the extreme."

He was a director for the Bank of Upper Canada and also for the British America Fire and Life Assurance Company.

Over the years, he was engaged in a variety of community organisations, such as a trustee of the Home District Grammar School and the general hospital.

In 1836 he finally achieved this goal, being appointed through the influence of the Colonial Secretary, Lord Glenelg, who was a family connection of Dunn's sister.

However, just three weeks after his appointment, all six of the Councillors resigned when Lieutenant Governor Sir Francis Bond Head refused to take the advice of the council into account with respect to the governing of the province.

[1] Sydenham appointed Dunn as receiver general and a member of the Executive Council of the Province of Canada on the day the union was proclaimed, February 10, 1841.

Dunn and his fellow Reform candidate, Isaac Buchanan were even shot at, and a man was killed, at a campaign event in the streets of Toronto.

[9] Charles Dickens, who visited Toronto the next year, recounted the events: It is a matter of deep regret that political differences should have run high in this place, and led to most discreditable and disgraceful results.

It is not long since guns were discharged from a window in this town at the successful candidates in an election, and the coachman of one of them was actually shot in the body, though not dangerously wounded.

[12] Matters came to a head in late 1843, when the Reform ministry led by Louis-Hippolyte LaFontaine and Robert Baldwin resigned from the Executive Council, in protest against the refusal of the Governor General, Charles Theophilus Metcalfe, to consult with the ministry on government appointments.

[1][15] Dunn's son by his first wife, Lieutenant Alexander Roberts Dunn, an officer in the 11th Hussars (Prince Albert's Own) cavalry regiment, received the Victoria Cross for his valour as "the bravest of the brave" in the Charge of the Light Brigade at the Battle of Balaclava.