All Sikhs with their ceremonial knives should be deported from UK!
I did see a few Sikhs in the British Army & I never saw them carry a knife,
I also remember seeing a lot of Gurkhas when I was on a course with 2 of them & they never carried their famous Kukri outside in public unless of course on public duties
So I don't see these Sikhs should be allowed to carry one outside in public