Good day
(but not for me, as I was struggling and have only just finished)
Those Royal Engineers turned up again (they were in Saturday's crossword and I should have remembered, but sadly I forgot)
Although I have an answer for 17d, I still cannot see the wordplay apart from the "yet"!
This is just not my week :(
However, the sun is shining and I am off out for some fresh air :)
Jazzgirl