At the moment 'most' games are rated by PEGI (Pan European Game Information system).
Some games (with more adult content - totalling about 3%) are rated by British Board of Film Classification (BBFC)
This consultation is about having one set of codes that everyone sticks by.
Bear in mind that one is a European rating, and one is a British rating. What may be acceptable to some Europeans may not be acceptable to British people (eg law in Spain allows 14 year old girls to have sexual relationships).
They are looking at 4 options:
A hybrid BBFC/Pegi system.
Pegi ratings only.
BBFC ratings only.
No change except for the introduction of a scheme to ensure shops and suppliers comply.
http://news.bbc.co.uk/1/hi/technology/7533462. stm
Don't know which paper / publication you are reading that mentions the Manhunt game, but maybe you should read a better publication?