He was educated at St Peter's School under the guidance of his teacher, Richard O'Sullivan[2] and where he knew another later Cabinet Minister, Joseph Tole.

[2] Sheehan was also active in promoting secular education and widening the franchise but he wanted only one system of Parliamentary representation, the abolition of separate Māori seats and the end of plural voting.

He was one of the first ministers to advocate breaking up of the large runholder monopolies which he believed had created a social elite at the expense of the normal citizen.

[2] Sheehan died of pneumonia and cirrhosis of the liver in Petane (now Bay View) on 12 June 1885 aged 40 years.

[2][7] In 1890, his widow, Lucy Caroline Sheehan, married Herbert Samuel Wardell, previously a resident magistrate of Wellington.