The same databases that allow you to resolve geoip location typically also would get you ASN for free and then you can try to filter out obvious non-residential IP blocks. Just looking for M247 alone (major bulletproof hoster frequently used by VPN companies) would probably detect at least half of all commercial VPN IPs including most of Nordvpn's.
I read up on ASN (Autonomous systems numbering) and M247 as well.
Is there a way I can camouflage my IP headers so that BBC won't detect M247? Would using different protocols which NordVPN offers do any different - SOCKS, P2P?
Thanks for your suggestion again.
Try a different VPN and pay close attention to server IPs and their whois. There are some real shady ones whose "server" pool is essentially malwared unsuspecting internet users, that should get you a residential-looking IP rather than datacenter.
You can't write the wrong address on a letter and expect it to arrive at its intended destination. You're already doing the most you can, routing wise, but a direct line still has to be made back to you... be it behind a proxy or not.