Well, Netlify itself might have some kind of configuration for your domain, but currently when I trace it, it's just saying AWS, AWS and more AWS. Except for the SOA record.
However, that SOA record was coming from an AWS nameserver? That's not how it's supposed to work. If you want to change DNS from AWS to Netlify, you need to change the authorative DNS servers at the DNS registar from AWS to Netlify.
My colleague has just spotted something inside AWS. Although I had changed the settings in the hosted zone there is an additional place to configure the name servers under 'registeted domains' in route53 - these were still pointed to AWS' NS servers!
I've updated them now, so fingers crossed we come good.