What should be done about extremist Muslims like this in the UK? are they now ruling the roost?

They are almost there. Their avowed intention as displayed on their placard for all to see is "ISLAM will dominate the world - to hell with freedom". They want to dominate us. Once they achieve their aim, you can kiss goodbye to free speech. In Malaysia where muslims dominate, they won't even allow Christians to use the word "Allah" to refer to God in their Bibles even though Arab Christians have been using it before Mohammed was born. How to deal with them? Clearly if they are not happy in the west, they should go to the many muslim countries where their extremist views are the norm. Such as Saudi Arabia, Somalia or Iran.