The authorities discover that the Earl of Warwick (a genuine
claimant to the throne) and fellow prisoner Perkin Warbeck had
attempted to escape from the Tower of London, and the pair are
re-imprisoned.
Citation:
Editors. "Conspiracy to release Perkin Warbeck from the Tower is discovered".
The Literary Encyclopedia. First published 01 November 2010
[http://www.litencyc.com/php/stopics.php?rec=true&UID=14010, accessed 22 May 2013.]