[mykalberta]

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There should be some great deals to London.

I tried some of the advertized cheap ticket sites, I found that going directly with the Airline is normally the cheapest.

For Calgary you are looking at the following options to London.

Direct: Air Canada, British Airways, Air Transat.
Connecting: Lufthansa, KLM, Air France, NWA, etc.

Also might be worth a look to see what the fares out of New York area as Air Canada, Westjet and Continental all fly direct from Calgary to the New York area.