The Groom of the King’s Close Stool, or just Groom of the Stool, was a job that made the holder quite “privy” to the monarch. And we use the term “privy” in its literal sense since that was where it was performed. And, as one person pointed out, the Privy Counselors were originally in with the king whilst he did his business.
While I forgot the precise title of the job and used the search term “wipes king’s arse”, a better informed source says this might not be correct:
Of course, one might hope to be reimbursed handsomely for such a role, especially if the Groom actually cleansed the royal posterior himself. In all fairness though, there are no historical records to suggest that the Groom went to these extremes, although he would have almost certainly helped the monarch undress for each occasion.
This position was abolished by Edward VII in 1901.