Actually, Bedford does give more detailed figures. 16.47 feet (4.95 meters).
http://www.bodyflight.co.uk/faqs/
From the colourful answers in this thread, one could imagine this issue beeing a taboo and that there are people thinking this sort of question should not be raised.
Again, I wasn't seeking for information to judge one beeing better than the other. Just curious because THEY BOTH DECLARE THEMSELF AS THE BIGGEST! Lot of people thinking about this, because the difference seems to be so marginal. But if it's a taboo... well, let them keep thinking then!
Since any confirmation about the XP size has not been given, one might think the information on their website is accurate and therefore BEDFORD IS BIGGER! And even more likely, THEY BOTH ROCK!