Yawn.
You are absolutely right Treesa, the law is couched in general terms so does not refer specifically to butlers, maids, nannies, au pairs or any other sub-category of domestic servant.
For clarificaton, this whole thread has only been about the situation in the UK so legislation in other countries is irrelevant.
You should be aware that the NMW does not refer specifically to au pairs either, so are you saying that it doesn't apply?
For reference, this is the text in the NMWR 1999 which provides the exemption for au pairs...
(2) In these Regulations ?work? does not include work (of whatever description) relating to the employer?s family household done by a worker where the conditions in sub-paragraphs (a) or (b) are satisfied.
(a)The conditions to be satisfied under this sub-paragraph are?
(i)that the worker resides in the family home of the employer for whom he works,
(ii)that the worker is not a member of that family, but is treated as such, in particular as regards to the provision of accommodation and meals and the sharing of tasks and leisure activities;
(iii)that the worker is neither liable to any deduction, nor to make any payment to the employer, or any other person, in respect of the provision of the living accommodation or meals; and
(iv)that, had the work been done by a member of the employer?s family, it would not be treated as being performed under a worker?s contract or as being work because the conditions in sub-paragraph (b) would be satisfied.
(b)The conditions to be satisfied under this sub-paragraph are?
(i)that the worker is a member of the employer?s family,
(ii)that the worker resides in the family home of the employer,
(iii)that the worker shares in the tasks and activities of the family,
and that the work is done in that context.