I can add one small detail to Radtel's expert analysis.
There is also a tiny airport in London, Ontario (YXU). The main passenger traffic is from YYZ.
I don't know anything about booking with AVIOS points. I only raise the point because there will be some connecting passengers on the BA flight withYXU as their final destination. Do not waste any AVIOS points for a tix. to/from YXU. Just know you can fly there - in addition to taking ground transportation.