Cato-Street Conspiracy, an insignificant, abortive plot, headed by one Thistlewood, to assassinate Castlereagh and other ministers of the crown in 1820; so called from their place of meeting off the Edgeware Road, London.
Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)
Cato, Marcus Portius * Catrail