
Back when I was a very casual attempter at the Listener, I did manage to complete one of Waterloo's crosswords (3959: And Now We Are Twelve), and a fair bit of 3928: OO Spectacles. I found working through the solution to the latter one of those really fun and enlightening.
An Additional Symmetry appeals to me straight away - I have a great interest in symmetry and topology, and this puzzle fits into the C4 point group - everything can be rotated by 90 degrees including the orientation of the clue numbers. Fun!
In the effort of wanting to seem like a symmetry smartypants I tried to complete the gridlines before I even got going. And following the unwritten rule, (s)PORTED is the answer to 1 across, and in we go. 2 down probably crosses with 1 across, and is D,(r)ETRO,P. Write it in as 2 down checking the D at the end of PORTED. Should be able to fill in a few now... I had 6 as PORTER thinking it was a triple definition, but much more confident on 36 as EL,IDE(a)S. So 35 down has to start with S... SEDILE (LID rev in SEE), good good.
Hey, DE TROP is PORTED reversed, and SEDILE is ELIDES reversed... is there going to be additional additional symmetry? Might it be crazy enough that the four quadrants themselves have some sort of symmetry? If that is true, then I probably have some six-letter words joining up to thr outer squares... 15 across looks like EG,I,L in MP (finding out that David Cameron is the leader of the opposition in England right now), and that would fit tantalisingly with that P in PORTED.
And this is where I came to a grinding halt. I had a bunch more words, but I couldn't make them fit, particularly ARMCHAIR which was one of the first cold solves I got, wouldn't cross anywhere that made sense. I had another grid that tried to force these words in but I think I threw it out, I meant to trash it... the grid you see above was returning to the ones I was sure of at this point.
Oh... what if these reversals of each other are meant to go on top of each other? Then the grid opens out more... That would make PORTER wrong, since I had (he)REWARD for 18 down it would be DRAWER (double definition). Start again!

Things started settling into place nicely when I figured that out. The big steps were fitting in the eight 5-letter entries that started at the same numbers into the words around the outside. I had to hunt and peck to find the last few words (IGARAPE, TRENCHARD, GARRY OWEN), but once the symmetry was in place, things fell out in a rapid tumble.
A very fun puzzle that was right up my alley, there's been a few of those lately, and nearly caught me. Victory to George! 2009 tally: George 9, Listener 1. Current streak: George 3.