Can someone lawfully ban you from taking a picture of your own child?

My 7 year son have been part of a UK based Karate club for the past 3 years and each 'grading' (ie when you go from a belt colour to another) parents are invited to the ceremony. It's a great moment where child and parent are very proud and for me, as an amateur photographer, a great photo opportunity.The club have hired a 'professional' photographer at the past grading (by professional I mean someone with a camera) and have started offering photos with a high tag price. So far so good, that doesn't bother me. If anything, it's great that the club is offering the possibility for any parent to purchase a decent professional photo of their child.Today I receive an email from the club saying that absolutely no photography allowed apart from the professional photographer (to an extent that they will put stickers over phone camera etc). They say this policy is put in place "in order to protect the privacy of potentially vulnerable individuals".I'm very annoyed at this but can't quite pin point a way to respond to them. How would you as a parent or photographer wanting to take picture of your child react to this scenario? Can a club ban you from taking photos of your own child? Is this even legal considering these grading ceremonies are done in a hired Parish Council hall and not the club itself? via /r/Parenting http://ift.tt/2h747t5