When the New Zealand Constitution Act 1852 became law, Pollen was made chief clerk in the Auckland Superintendent's office. From there, he rose through the ranks. Two years after his original appointment, he was appointed to the Executive Council, and in 1858 he was appointed Commissioner of Crown Lands for Auckland. In 1856 he was elected to the Auckland Provincial Council for the Suburbs of Auckland electorate, where he served until 1861. From 1862 to 1865, he represented the Auckland East electorate on the council.