Some thoughts on the Common Toad

Yesterday Bob from Brockley quoted George Orwell from 16 May 1939. A few years later Orwell observed in his essay Some Thoughts on the Common Toad that:

Even in the most sordid street the coming of spring will register itself by some sign or other, if it is only a brighter blue between the chimney pots or the vivid green of an elder sprouting on a blitzed site. Indeed it is remarkable how Nature goes on existing unofficially, as it were, in the very heart of London. I have seen a kestrel flying over the Deptford gasworks, and I have heard a first-rate performance by a blackbird in the Euston Road. There must be some hundreds of thousands, if not millions, of birds living inside the four-mile radius, and it is rather a pleasing thought that none of them pays a halfpenny of rent.

There were a number of gasworks in and around Deptford so it is difficult to be certain which site Orwell was referring to.