Thanks guys!
I ordered from Amazon.ca.
A breakdown of the figures reveals that £6.46 is attributed to import vat, and a whopping £3.85 clearance fee levied by the PO, making a total of £10.31!
The actual item cost $97 Canadian, which works out at approx £40, so if I do have to pay up, I'll be paying the same as what most other companies are charging, namely £50.
The good thing though, is that if you get away with it, you save £10, but even better, Amazon package their dvd's really well, so you're not going to receive a damaged tin!
By the way, how much is the import duty supposed to be anyway?