I didn't get to start this until 11.30pm (life is very hectic) and I actually found it easier than many prizes and really enjoyed finishing most of it last night with the final PDM this morning (this is unusually quick for me).
I didn't know that 27a was a capital office building but there is a car park with the same name where I live so it clicked quite easily. I parsed 24d as 1,4 where the 1 is the smallest amount that the debtor could be in debt for (in the UK)