Duty free when returning from canada and changing flights?

i am going to be returning from vancouver to manchester changing flights at calgary and heathrow. my question is can i buy duty free at calgary (alcohol and perfume - liquids) and legally get them through security at heathrow on my way back to manchester? i wont have my hold luggage with me only hand baggage, but. if i get them appropiatly sealed tamper proof etc and with receipt will it be ok?