This is terrific feedback, thanks so much Alex! Really constructive and useful.
I think you're right about the flagging in the first chapter - it needs tightening up and it's a fine, difficult line to walk, establishing character, injecting a little humour while keeping the pace going. I clearly haven't got the right balance yet!
And I'm sure you're right about the Christie references - imagine the complaints on Amazon if I ever got this published and got it wrong! I'll take another look
I'm so glad you enjoyed some of the banter. I like the relationship between Caro and Neil, that bickering you get when you've known someone years, people who are naturally, relaxedly humorous with each other. The agent that requested the full on this said she liked the voice, so I guess I've got that right, even if I have a lot of work to do structurally.
Thanks for taking the time to read so thoroughly and feed back. Really grateful