I enjoyed this. I managed all except 26a & 3d, but I eventually resorted to this forum for help. (I like to treat it as a last resort.) Thanks to Jono, whose hints enabled me to solve those two. The answer to 26a was such an obvious word to consider that of course I'd thought of it, and wondered if it was right, but the clue seemed too vague for me to be sure. I hadn't spotted the theme, but once I did see it the idea for 26a became obviously right. However, I still regard the clue as weak. For 3d too I had thought of the right answer, but didn't understand why, as I hadn't thought of the correct meaning for "bases". However, that is really such a standard type of crossword-clue use of the word that I'm slightly ashamed of myself for not thinking of it.