Frederic William Whyte, Dictionary of National Biography… (1893)
“ He was one of the first to impress upon O'Connell the desirability of wresting Clare from William Vesey Fitzgerald [q.v.] on the latter's accepting office as president of the board of trade in the Duke of Wellington's administration in 1828, and, as soon as O'Connell had decided on the struggle, Mahon spared no pains to secure his victory. Not content with ordinary electioneering tactics, he exploited to the full the eccentric resources of his own picturesque personality. ”
