Uneven lighting appears to be a feature of the London metro area: here's Wandsworth Common from the same trip (month is October)
Battersea Park - was almost impossible to see the station until you were in it: Hope you don't mind me dropping these in as I go, I'm travelling around with the snipping tool open on a separate window to try and capture these as much as possible!
I found that in october, the bulbs will go on beetween 18h10 and 18h15. And its already night far before. After 18h15 you ll find all platforms well lit. I found that same problem with bakerloo line. Bulbs start to emmit light too late at certain month. So municipality are scarse on electricity
After a litlle more of testing i confirm that this problem is on all British lines I own (GWE, BKL, CCL, LBN) It seems not a problem on German add ons however...