[1] In 1830 Sheehan joined the Comet Club of young Irishmen, with Samuel Lover, Joseph Stirling Coyne, Robert Knox who became editor of The Morning Post, and Maurice O'Connell.
The club issued pamphlets attacking the tithe system; the first, The Parson's Horn Book, which appeared in two parts with etchings by Lover, was popular.
The club then issued The Comet, a satirical weekly paper opposing the Church of Ireland, with the first number appearing on 1 May 1831.
[1] Shortly after 1868 Sheehan married the widow of Colonel Shubrick, or Shrubrick,[2] a wealthy Anglo-Indian officer, and spent some years in travelling on the continent.
[1] William Makepeace Thackeray knew Sheehan well, and he is believed to be the original of Captain Shandon in Pendennis.
Two other Irish friends, William John O'Connell and Andrew Archdeckne, suggested Costigan and Foker respectively.