In the UK, most of the major supermarkets sell ONLY halal meat (they don't advertise the fact though) in order to cover all religious requirements. So I imagine that restaurants of any kind are more or less obliged to purchase meat from animals slaughtered in this way.

I think it's deplorable. I don't agree with halal methods of slaughter.
The Government rules about slaughter procedures used to concentrate on humane stunning pre-killing, and on hygienic standards. Now, they seem to be bowing to minority religions and putting their rules above humane ones.

My husband's a Muslim, so he's obliged to eat only halal stuff.
I eat very little meat nowadays.