Cryptic crossword No 3,571

Ah! After your comment I was keeping an eye out for a grid! Some really tricky ones here, I fear my Geography and Literature rounds are a bit weak in the pub quiz for this one and I'll admit to looking a couple facts up to check. Favourites 1d 11a 7a (very satisfying when it fell into place) and 13a (very drole!). Is the extra ? In 20d because "Attila?" Is dbe? Personally I don't think it needs both. Also very creative 22d, but also very tricky :) thanks for the puzzle!

Very tricky indeed ! Afraid my study of Blake was too long ago and too superficial to make his idea appear early. I especially liked 13a,23a,3d,14d