I can't see why the membership secretary is any different from the rest of the board. Decisions about membership are made by the whole board, so everyone has access to the information. If the mem sec needs a check, then the whole board does. From my research, I don't think it is absolutely necessary for the board to be checked (unless they are going into schools to teach people about using Wikipedia, or whatever, which can be dealt with at a later date), the question is whether it is a) desirable and b) legal to run the checks. I don't really have an answer to that.