Probably related to the recent ASA guidance / rules on advertising as regards speed - there's a news article on it on the main site here:
http://www.thinkbroadband.com/news/5135-is-speed-to-...
That said - I don't see any mention of either 38Mbps or 40Mbps on the page you linked jsut this:
"BT Infinity – it's our fastest ever broadband
Four times faster than the UK average"
Of course, the average speeds on Infinity are nicely skewed upwards by not allowing anyone they think will get <15Mbps to sign up.
Edited by GeeTee (Fri 06-Apr-12 22:33:12)