I've done some research on what the different producer's say on their websites:
Hipp website instructions
"Boil freshly run tap water and leave to cool for less than 30 minutes." then a bullet point "?Prepare feeds freshly and not in advance. Powdered milk feeds are not sterile and reconstituted feeds are at risk of infection with E.sakazakii "
Aptamil website instructions
"Boil freshly run tap water and leave to cool for 30 mins, unless otherwise indicated on pack."
SMA website instuctions
"Boil fresh tap water in the kettle and allow it to cool to no less than 70 degrees C (this means leaving water to cool for betweeb 25 and 30 minutes after boiling)."
Cow and Gate website insructions
"Boil freshly-run water. Leave the kettle to cool for 30 minutes. Do not use artificially softened or repeatedly boiled water."
So it looks like SMA has the best description.
(And of course in my webchat Aptamil were spouting on about 70 deg being the "optimum" - but wouldn't explain why this was not on the packs!)
Baby Milk Action talked about this issue nearly three years ago. (NB I guess the info on that link about HIPP is now out of date).
The NCT issued a press release about it over 2 years ago - it looks like some change have been made to talk abut the 30 mins, but not in most cases the 70 degrees.