This week's puzzle is by Picaroon and, although I'm not very familiar with the different setters, I'm sure he/she is a regular for the Guardian.
I found this quite difficult but, as always, once it's been solved it's difficult to see what it was that caused the problems.
That said, a lot of the parsing is quite intricate, 20a for example. where you have to piece together five separate parts.
There is no particular theme that I could see but there seems to be a scientific bent to the puzzle. 17a for example, should please Chris, our resident chemist and I knew 27a from a lecture I attended at the Planetarium by Michio Kaku.
My FOI (First One In) was 2d, quickly followed by 22d and 23d.
I'm just re-reading Wolf Hall so was pleased to see 7d get a mention.
There is a long anagram if you get stuck but don't do what I did and dismiss the one answer the anagram solvers return - it is right!
COD (Clue Of the Day) lots of contenders, 13d, 7d and 14d but I'm going for the excellent 25a.
It's great that more and more new solvers our joining our friendly discussion thread each week, and if you get stuck, don't hesitate to ask for a hint, there are always people willing to help - you might be one of them:-)
Thanks to Picaroon for an excellent puzzle.
Stay safe:-)