The website for the Social Security Administration has much useful information. The site is www.ssa.gov . Below is one faq that may be relevant to you. You should check with SSA or an attorney to find how the laws applies to your particular case.
If I leave the US, can I continue to receive benefits?
If you are a United States citizen, you can travel or live in most foreign countries without affecting your eligibility for Social Security benefits.
However, there are a few countries–Cambodia, Cuba, North Korea, Vietnam and many of the former U.S.S.R. republics (except Armenia, Estonia, Latvia, Lithuania and Russia)–where we cannot send Social Security payments.
If you are not a United States citizen, the law requires us to stop your payments after you have been outside the United States for six consecutive calendar months unless you meet one of several exceptions in the law which will permit you to continue receiving benefits abroad. These exceptions are based, for the most part, on your citizenship.
For example, if you are entitled to worker’s benefits and are a citizen of one of the many countries with which the United States has a reciprocal arrangement to pay each other’s citizens in another country, your Social Security benefits may continue after you leave the United States (see a list of countries where we can send payments inYour Payments While You Are Outside The United States, Publication No. 05-10137). If you are planning to be outside the United States for six consecutive calendar months or more, you can find out if you can receive your Social Security payment by using the Payments Abroad Screening Tool.
If you work outside the United States, different rules apply in determining if you can get your benefit checks. Most people who are neither U.S. residents nor U.S. citizens will have 25.5 percent of their benefits withheld for federal income tax.
For more information about receiving benefits abroad, we recommend you read the booklet, Your Payments While You Are Outside the United States (Publication No.05-10137) and International Agreements, Payments Outside the United States, and Social Security in Other Countries at http://www.socialsecurity.gov/international/.
The answer is a qualified "yes" that you can receive benefits without becoming a US citizen or residing in the US. But you need to check this with the Social Security Administration - you can call their toll free number 800-772-1213 for an answer that will be tailored to your exact circumstances.
Additionally, you should definitely review this document which delves into the US/UK Social Security Agreement which allows you to possibly even combine your US and UK retirement credits.