expired passport..

My Canadian passport expired in March but I still have an Ancesteral visa..how to I apply for a new Canadian passport in the uk (scotland) without loosing my valid visa?

Typically, if the visa cannot easily be removed from your current passport, you leave it in the old and carry both until such time as an immig officer either issues a new visa, moves it in your new passport, or leaves it as is, in which case you continue to carry both old and new.

You will apply for a new passport thru the High Commision in London.
Ask them.