In his early days in Tasmania he spoke too frankly about the colonists in communications which he regarded as confidential, and this accentuated the feeling against him as a representative of the colonial office during the anti-transportation and responsible government movements.

In New South Wales his task was easier, and he had no difficulty in coping adequately with the problems that arose during the early days of responsible government in Australia.

Of note, Denison carried out experiments under the direction of Lt. Col. By to determine the strength, for construction purposes of the old growth Canadian timber in the vicinity of Bytown.

[4] Denison was offered the position of Lieutenant-Governor of Van Diemen's Land in 1846 on the recommendation of Sir John Burgoyne, and arrived at Hobart on 25 January 1847.

Six members of the nominee Legislative Council had resigned in protest over the costs of the prison system, which was partly borne by Tasmanians, and increased by the suspension of transportation to New South Wales.

There had been a strong protest from members of the Anti-Transportation League and Sir John Eardley-Wilmot had been recalled for his failure to administer.

Due to difficulties in appointing replacements, Denison chose to rule without a functioning Council, even though this meant he could not pass legislation, including that needed to amend some local tax laws that were subsequently found to be faulty.

He suggested that the Chief Justice should apply for leave of absence, and also found an opportunity to dismiss Montagu who was threatened with an action by a creditor.

Denison was afterwards reprimanded by the Secretary of State, Earl Grey, for his conduct towards Pedder, but the dismissal of Montagu was confirmed.

The Anti-Transportation League formed to oppose transportation had the support of nearly all the leading colonists of Tasmania, and as the other colonies took the same stand success became certain.

The discovery of gold in Australia, reduced crime in England and the construction of prisons in England led to a decline in the convict transport and in 1852 Lord Stanley stopped the transport of prisoners to Van Diemen's Land and Denison closed the penal settlement on Norfolk Island.

He inaugurated the bicameral system of representative government in New South Wales, and showed wisdom and tact in his dealings with the problems which arose, including the handing of executive power to the new Parliament.

While he opened the colony's first railway in 1855, he ignored the problem of different rail gauges despite his role as Governor-General, although he was more active in developing arrangements for paying for postal connections with the United Kingdom, ameliorating inter-colonial tariffs and co-operation over the provision of lighthouses.

He opposed separate armies for Bengal, Madras and Bombay and the introduction of Indians into the legislative councils in the presidencies and provinces.

[4] The Institution of Civil Engineers in the United Kingdom bestowed upon him the prestigious Telford Medal in 1837 for his paper on his experiments testing the strength of Canadian timber.