Unfortunately English law around intruders in the home is quite vague and very different from the Castle Doctrine laws in the USA

'As the law currently stands, a person in possession can use no more force than they reasonably believe necessary to remove a trespasser from the premises'

http://en.wikipedia.org/wiki/Defence_of_property

People have been convicted of using force against intruders in their home. However, a group of angry rioters is somewhat different.