I don't know where it says that you are moving to Calgary - I'm missing something? Mercer publishes a pretty good guide on cost of living - I'd say that Toronto is 90% on London (depending on how much you like cheese and wine / and beer!). Neither myself not my wife took a pay cut when moving from London - but it depends on your industry I guess.

Anyway - it's easy to go out a market value yourself using tools like salary wizard, which I think is available in workopolis