Ooof...finished..... at last. A struggle all the way, from the moment I tried to print out the puzzle, but couldn't. It wasn't made any easier by my putting the engineer in at 22d (a valid answer, I'd say, as the clue stands), and chucking in "AA Milne" on a wing and a prayer for 28a (which wasn't [a valid answer]). Still, all's wells that ends wells.