It is not. We seem to have to go through this at every product release.
Code:
US UK Euro (Fr) UK Premium EU Premium
MBP17 £1572.74 £1701.28 £1677.55 £128.54 or ~8% £104.81 or ~6.6%
Apple want to set a price for their product which can remain constant for as long as possible, they also want to market their product at a specific price point in whichever market they're competing in. To do this they have to take into account various factors, one being exchange rates and they build in a margin of error so that if exchange rates move against them they don't have change the selling price to avoid reduced profit. I think 8% is probably a fair premium to pay considering the smaller market in the UK and additional cost incurred selling there.
If you do a search I did the same comparison over a year ago on some other products (displays I think) and Apple actual gave a better deal to the UK than it was to the US at the time. Also compare DELL's products in the UK/US and you'll see much biggar differentials.