It is a stinker too !
There are 21 answers missing two letters which gives three groups of seven but there are six missing three letters and one missing four (8D). Has something gone wrong ? The three letters missing are DOC -- the compiler's name--- and the two letter ones are similar letters meaning doctor i.e MO, MB and (Dr) NO
e.g. 9ac (DOC)torial 25ac (NO)strums 24d. cru(MB)s and 19d demi (MO)ore. Knowing this much though I am still having great difficulty in getting most of the answers !
Ulysses, I think 2dn should be 7 letters instead of 8. This wuld mean there are seven "DOC"s in the puzzle. I've got bulDOCk for this clue but can not get an answer for 8ac so can not verify this.
Quizmonkey, the answer you give is unfortunately wrong. The check letters I have are A?R???, so doctorial can not possibly be right as this would be entered as "torial".