B1/B2 visa holder / Dual Citizen / ESTA confusion with VWP

Hi,
I'm really confused: I hold dual citizenship (UK) and therefore I can enter the US using the Visa Waiver Program.

However in my other passport, I have a valid B1/B2 visa (Until august) issued by the London consulate.

Now, two questions:

Since I'm British and I live in the UK, I want to enter the US as a British National, given the fact that I'm a US Visa holder with my other nationality, is that going to be a problem? My fingerprints are associated to the B1/B2 Visa.

The other question, when checking ESTA it clearly says "US Visa Holders shouldn't use this service", but technically speaking I'm not a Visa Holder under my British Citizenship.....Shall I use the ESTA?

I'm thinking on travelling with both passports and explain to the IO at the port of arrival, but I'm not sure of the implications of doing that.

Any advice will be appreciated.

You need to contact the US consulate/embassy nearest you and consult with them. Don't leave it until you board an airplane. The check-in staff might be confused and not know what to do and you might be refused boarding.
Even if you get to the U.S. port of entry, the CBP officer may also make trouble.
Whatever info you get from the embassy or consulate, make sure you get it in writing, so you if you cannot register with ESTA you can present the info at check-in or to to the officer at the port of entry in the U.S.
Specifically with U.S. immigration you have to dot all the i's and cross all the t's, so to speak

If you have a valid B1/B2 visa and are visiting the USA before its expiration date, then why don't you simply use the visa instead of the WWP?

Thanks for the replies guys.
As lifeart said I may have to contact the US consulate.

Vinny, the reason of why I want to use the VWP is because I would like to enter the US as a British Citizen. My B1/B2 Visa is in my other passport (different nationality) so not sure of the implications, specially if I need consular assistance from the British Authorities in case of emergency.

Cheers.

Apologies, please ignore the above, completely misread the OP as saying one of his/her passports was a US passport.