However US pricing is normally exclusive of tax whereas the U.K. price is inclusive of 20% VAT. 54*1.2 is around £65 so not that far off the £67 price.
However, there's a simpler reason: for psychological reasons no retailer is going to voluntarily put higher prices on their shelves than they have to, and since unlike most other countries there is no consumer protection law requiring the the actual checkout price including sales tax to be displayed, they don't.