By Bradley Jolly The ambassador of King Charles’ anti-violence charity has been caught on camera appearing to slap and assault a man. Rahat Fateh Ali Khan, a global music star, appears to rain blows on the victim – a backing singer – with a slipper in a hotel room and drags him around by his hair in the shocking clip. The Pakistani folk singer, 49, last night admitted the assault – and the monarch’s charity, the King’s British Asian Trust, said it is investigating the matter. The charity, which helps domestic violence victims and runs mental health and poverty initiatives across India and Paki…