How effectively has Kick-Ass been regulated?

For Kick-Ass, the British Board of Film Classification awarded the movie an age 15 rating. Considering the content of the film, this is perhaps rather surprising in comparison with other movies with the same rating. 

To have an age 15 rating, it should encounter:

• No dwelling on infliction of pain or injury
• Violence considered contrived and over the top is it not considered realistic 
• Comical violence 
• The context of the film in relation to it's content 

When looking at the elements to an age 18 rated film, it would seem much more appropriate:

• Strong language and discrimination
• Real sex
• Extreme gore and horror
• Graphic violence
• Strong violence
• Frequent sexual language

The representation of Hit-Girl embodies all this, with extreme acts of violence and language including 'c**t'. However put into context the genre and themes of the movie, and it is easy to remember that the violence may be considered over the top, or being overly comical. One scene in particular is when Hit-Girl is beating up grown men to the Banana Splits. As Christopher Tookey puts it, "it deliberately sells a perniciously sexualised view of children and glorifies violence, especially knife and gun crime, in a way that makes it one of the most deeply cynical, shamelessly irresponsible films ever".

One of the key arguments in awarding the film an age 18 rating is one of the final scenes in the film, through the kidnap of Big Daddy and Kick-Ass. This scene lasts for a prolonged amount of time, and almost definitely "dwells on infliction of pain or injury". A key moment in particular is when Big Daddy is set alight, and for a few minutes we watch him eventually burn to death. However, if the film had indeed been awarded an aged 18 rating a huge chunk of it's target audience would have been considerable missed out. Undoubtedly the film is aimed to teenagers, yet surely it is not justifiable to have such content displayed to a younger generation.