The amendment to the ANO can be found
here.
I was slightly incorrect in my previous post. The amendment came into force on the 15th March 2007 but table 3 within the amendment actually says
on or after 1st January 2007 when at a distance of more than 10 minutes flying time at normal cruising speed away from land suitable for making an emergency landing
it then goes on to quote KK 1 or 2 which is an ELT conforming to certain specifications.