My British passport has expired here in America.

Usually one has to contact the nearest consulate rather than go back to one's home country. That one would send a passport back to England sounds unusual. New passports are exactly the kind of service that consulates are there for! But anytime dealing with officials about passports and citizenship one needs to be open about having any multiple passports. It has to do with many factors - but not terrorism. But one's citizenship status is not dependent on having a valid passport or not. The British consulate responsible for Texas is in Houston: https://www.gov.uk/world/organisations/ … al-houston

Any retirement benefit considerations should be looked into by contacting the proper authorities. Social Security benefits and taxes are regulated by what is called a totalization treaty. I am posting links to the specific IRS and SS websites dealing with the agreement between the US and England. You should get informed about such things independent of having a valid passport.

https://www.ssa.gov/international/Agree … ts/uk.htmlhttps://www.irs.gov/individuals/interna … agreements