Thanks Jono. Going back through former PMs finally got it for me. Apologies if this appears twice but posted once and it didn't appear. After thinking it must be an obscure word I didn't know, 26a is actually one of my CODs. Alongside 22d because who doesn't love a good Spoonerism.
Getting the theme was key for me. 10a was FOI and then when I got 16a it fell into place.
Thanks Kite for a more gentle challenge this week.