Wire transfer.
Get his bank info (including IBAN number), go to your bank, and initiate a wire transfer from your bank to his. Since this is your first experience with wire transfers go to your bank, tell them you are doing your first international wire transfer, get the form they use, and ask them to explain how to fill it out so you know what info you will need from MacKinlay to get the money transferred.
My bank charges me a flat $40 per international wire, plus a currency conversion fee if I want the funds delivered in the local currency of the destination.
