I was brought up in Hounslow, West London, about 2 miles from the huge 1920s marshalling yard at Feltham, where much of the Southern Region freight for London destinations was sorted out and transfer traffic to, particularly, the MIdland and Eastern Regions was marshalled into trains, some of which were collected or brought in by "foreign" locomotives. Midland 8Fs and occasionally a "Jubilee" or a "Crab" were seen, and there was a regular J50 working from the Eastern Region. At night, when the wind was in the right direction, I could hear the clash of buffers as wagons were hump shunted at Feltham. The Hounslow loop could boast four freights an hour at least, as well as the half-hourly suburban electrics in each direction, and Feltham yard's output had to fit in with these, as well as crossing the busy Reading and Windsor lines at the exit of the yard itself.
(Jan 2008. Not long ago I came across a book of photographs of London's railways from the air. There was a brilliant one of the yard when it was fairly new in perhaps the late 20s. You could make out a G!6 pushing a rake of wagons over the hump towards the western departure sidings, and an S15 waiting to set out to the east. Behind the yard, to the south, was what I only now realise must have been Hanworth Aerodrome, and there on the ground was the huge bulk of the Hindenberg airship, visiting from Germany. More on this when I've done a bit more research.)
I suspect this was actually taken on a different day, behind the shed, as the sun seems to be shining. S15 4-6-0 no 30842 waits for the coaling stage and ash-pit.
Another S15, this time no. 30496, which was shedded at Feltham for most of my youth, backs down onto its train past one of the diesel shunters which had long displaced the G16 heavy tanks onto freight duties.