BarbaraOcumbungles the site is American, e.g. see the spelling of center, the contact tel is a "toll-free" 0808 number operating on UTC. The size chart starts with US sizes and works along the various country conversions.
J Crew sell in exactly the same way in the UK except that explicitly state sizing is US above the size options.
Hope I'm wrong for those who have ordered incorrecty, not trying to piss on anyones bargain chips :)