Been doing a bit of digging -well , OK, googling - on this 'cos it intrigued me and turned up this:
http://www.dft.gov.uk/stellent/groups/dft_rdsafety/documents/page/dft_rdsafety_611257.hcsp
This is the official Department for Transport site and has all the info on the new regs that come into effect from Sept. this year.
Hope it helps answer the questions!!