I like Sickert a lot - but some of his paintings are so dark, tone-wise, darker than anybody elses I've seen I think. I guess London was dark then... almost invisible art right there
I know quite a few painters who really like Sickert's works. I do too. Yes they can be very dark alright. Did you know he was once suspected of being Jack The Ripper. I think this was bought up in the media recently.
I remember reading The Horses Mouth when I was a teenager and later learning it was based on Stanley Spencer. It was a funny book to read as a young person, but very rewarding.
The paintings in the film version of The Horse's Mouth were by John Bratby, who incidentally was in the same painting class at Royal College of Art as Joash Woodrow and Frank Auerbach. I can see something similar in the work of all three. Here's a Bratby: