Looks like Lexus GB don't know what the true stats are.
The link from Raz states 300 bhp for the 4.3 but their latest press release gives a figure of 282 bhp
http://www.lexus.co.uk/news.php?page=article&id=geneva
Sadly I feel the second figure will be the correct, the Euro version being 20bhp down on the US engine.