You can calculate 48 by 1 + 47 (ten words in total). However, 21 32 12 23 47 (nine words in total). The remaining unclued lights are the two authors who said so.

        Across

14    Not so sure judge needs latitude to be good (6)

17    Sacred halls rebuilt in poor area (7)

18    9 stocks such organs (4)

19    Woman wanting hospital to make changes (4)

20    Sign of aging, like an Irish circus, say? (4,4)

22    German idioms translated in the style of a letter (7)

26    Weather problem has troubled swimmer (6)

27    Bridge player quick to change lead (4)

28    Painting over withdrawn mixture (4)

29   ...