Like in the US it is hard to really find out what is what. In Canada the CFO thinks you need an import license but Global Affairs who looks after this says you do not and it is right in the literature and confirmed by their office. Have your PAL on you show up at the border and you are good to go if a non-restricted gun. Have them mailed to you, just the same. Coming from another country may require their export requirements. You do not need the services of Prophet River or I Run Guns. It may have to be brokered depending on the amount and who you have as a shipper. Use USPS from the US otherwise pay the price of using DHL or UPS who charge their own (exorbitant) broker fees. If you need Global Affairs contact, PM me. If you need full details for both the US and the UK PM me however it may be best to have a conversation instead of me writing a brochure.
Interesting fact....our firearms laws do not allow you to mail (Canada Post) a gun from Canada to any other country however you can have a gun mailed to you from another country.
