He was likely born Peter Vallely in Armagh, Ireland in 1799 possibly the offspring of a mixed Protestant/Catholic marriage, and moved to Liverpool as a child.
He joined the British navy as a cabin boy and jumped ship in Quebec City in 1815, changing his name to Aylen, thought to be his mothers maiden name.
Left idle near the end of winter, Aylen's men mounted a campaign of violence in the Lower Town area of Bytown during the late 1830s.
As a result of attempts on the life of James Johnston, who had written to the Lieutenant-Governor complaining about Aylen's activities, armed patrols were set up in Bytown, which put an end to the open violence there.
Aylen had leased a large property on the Richmond Road and also owned land in Nepean Township, acquired via marriage.