Some very clever clues this week, but much easier than last week’s.
On the matter of the plural of bureau, I put “x” (to add to the good spread of “x” in the crossword this week). It seems to be the trend these days to make all plurals by adding a “s” to the word, even if it is not traditionally accurate to do so. So, in a similar way, the dictionaries give both formulas and formulae as the plural of formula. There was a move some time ago in science teaching to use “formulas” but fortunately good practice uses “formulae”. But English is a living language so many would argue that both spellings are correct.