I'm sometimes asked if I have been CRB checked when I say "No, of course not" I get a funny look. However, when I explain what CRB is I get a very different response.
A CRB check is a query to the Criminal Records Bureau to see whether someone has a criminal record. No, I don't have a criminal record and I have nothing to hide but I see one key issue with the CRB question... it's only valid at the moment of the CRB query. So if I did a CRB check today, printed a confirmation, robbed a bank tomorrow, did a prison sentence and then tried to become a photographer with my CRB printout, I could still claim I has a CRB check. Used like that it's meaningless.
However, CRB checks are very useful from the client perspective to help confirm they are happy to have this person working for them. Schools will often undertake them before allowing anyone near children, and that makes sense. However when taking photographs for family occasions the dynamics are somewhat different. A CRB check is not as helpful as client references (particularly word-of-mouth recommendations/references) to ensure clients are confident you are reliable and professional, and of course will do a good job recording the special memory. When photographing children in particular I always expect parents or guardians to be present at all times... they know how best to get their children to respond positively, the children like it and of course so do the parents/guardians. I know I would feel that way if it was my daughter being photographed.
Since I know I don't have a criminal record I suggest to prospective clients that they can pay for a CRB check on me if they wish and if the response is not to their satisfaction I will cover the costs incurred... it's never been an issue.