I was right 1,15 and 5d were key but I fall for Tramp's brilliant misdirection every time. Not up to speed on my US novelists so 16d was my LOI. I also had the wrong first letter for 21d which meant that the very obvious 20a eluded me for longer than it should have.
FOI 3d. COD 5a for the clever misdirection.
Thanks Tramp. You had me guessing for longer than most it seems. Very enjoyable.