Well spotted Mattrom, I missed that too. There were a few I wrote in without stopping to parse and I still can’t see how 6d works in fact, but I’m sure it will click as soon as I post this.
I did notice that Everyman’s used this grid several times before for ‘alliteration-themed’ puzzles. C county council etc, G get the giggles etc, S secret service etc - all use this grid. And of course it only works when 1a is (6,7) so that the start of the second word is the start of 4d, as is the case in all of the above and today’s. Clever.