Is my licence valid?

[I have control]

I live in the USA and have got a CAA PPL from the UK, and an FAA licence that says it is based upon the restrictions attached to my UK licence. Yesterday my biennial expired on my UK licence. However I still have a year to run on the FAA biennial that I got last year. So the question is am I legal to fly here in the States on the FAA flight review, or do I need to find myself a British instructor to do my biennial.

Thanks for any help offered.