Who uses a credit card to view pr0n these days anyway?
Even the new stuff from p0rn site is available on forums within hours of it being published on the pay websites to download for free. Or just type whatever fetish your in to on Google images and let it come back with 1000s of hits
All this is going to do is create load of phishing sites that look like naughtyspankglrls.com but with a fake age verification page to harvest credit card details.
And unless the BBFC are suddenly taking on 1000s of new staff to monitor the millions of sites that peddle smut online there is no way they will be able to keep any sort of list up to date.