Brendan,
Overall it was slightly gentle, but my solving time was greatly extended by 18, 20, 24 and 26 in the SW quadrant. Otherwise it'd have rated as easy.
Struggled terribly with 18 and (especially) 24 (as you suspected) before pennies dropped. Suspected the solution to 26 right off but took ages to parse. Simply drew a blank on the rather straightforward 20.
Many delightful clues but a handful of "gimmes".
FOI 4, whose unusual wordplay has become trendy (ISTR an example in yesterday's excellent Fed).
LOI the unaccountable 20.
Got 7 quickly, but parsing eluded me until I noticed the clever paired clue.
Co-COD 17 and 18.
Also liked 5, 13, 8, 16, 12, 3 and 7.
Pangram head-fake...looked likely but a couple letters wound up missing.
Thanks to Philistine.