Cryptic crossword No 3,334

Thanks Lohengrin, plenty to enjoy and learn from here. The network beat me in 25a, the nho 16a needed all the crossers but was fair play, and the devilish device in 20a was a first for me and took some cracking. I thought 1a was as good as it gets for this device, and other standouts were 12a, 13a, 27a (neat), 14d, 18d, & 19d. Cheers!