Pursuant to the Boss's instructions not to start fresh lines of enquiry, but with considerable doubts as to whether this will work in practice,
I revive this thread as I am stuck in the bottom left corner. (Indeed, but for earlier answers I'd have been stuck all over the place.)
Perhaps assistance with these will spur what's left of my mind into some kind of action.....
31D - Poll advises changing filming technique (3, 8)
L?? ?I?????? [this looks as if it should be an anagram of POLLADVISES but if it is it's beyond me]
52A - Tips from mathematicians show square and cube root (5)
?????
45D - Doesn't eat in a flash brasserie in the centre (5)
?????
&, on the other side :
54A - May, perhaps, God enter in disguise (9)
??O???R?E
also, in the middle :
24D My rugby training base (7)
(C?R?U??) [if this is CIRCUIT why on earth is it?]
It's appallingly early in the morning, so I'll now pop off for half an hour or so (breakfast, etc) & hope that on my return better minds than mine will have woken up.