NS&I allow US Citizens to invest with them

Thanks for the advice - yes I still consider Premium Bonds to be a good investment, especially if you hold a good chunk of them - a prize fund of 1% from December with instant access is still not to be sniffed at - the only drawback is potentially winning the big one and paying a large slice to Uncle Sam - chance would be a fine thing and one to be tackled if it ever happens!

The prizes are to be slashed beginning Dec 1st along with NS&I other rates unfortunately.  This last couple of years the "imputed" rate on P Bonds has been 1.4% which is what you would make with "average luck".  The worry about the tax consequences of winning "the big one" does not weigh heavy on my mind. 

https://www.which.co.uk/news/2020/09/nsi-to-slash-nearly-30-million-of-premium-bond-prizes-from-december/