People really think Blitz-era Brits were so decadent? Look at how much cheese is on there! That's enough to give an elephant nightmares. And that's like half an onion!
Besides, London rats are a meal all in themselves. No need for fancy cheese and onion cobs when you can go to the bins behind your local and get a wriggling, squeaking meal washed down with some fresh bin juice for free.