He was both Minister of Railways and Postmaster-General and Minister of Telegraphs in the Second Labour Government from 1957 to 1960. As one of Labour's most experienced MPs Moohan naturally expected to be given a major ministerial portfolio. It was a surprise for many, and in particular himself, when he was allocated only two relatively innocuous postings. He was not even allocated a front bench seat and made no secret of his disappointment. In 1959 he travelled to Warsaw as a delegate to the International Parliamentary Union and then went to London to study developments in telephone cable and postal procedures. His main accomplishment was the construction of a state of the art rail ferry, the "Aramoana", to operate across Cook Strait.