Yes I had to do the same already 3 years ago. The TIN is your PPS number. I had to renew the W-8BEN forms this year and was still there. I'm also tax compliant however a friend of mine who works in the financial sector told me clearly that the U.S. adhere to their own scheme called FATCA which provides for tax information exchange with hundreds of countries but it's a one way scheme in favour of the U.S. only. In reality the U.S. while ask and require full info on accounts held by U.S. citizens abroad , they are exchanging no or very little information with third party countries on foreign nationals having accounts in the U.S.. He told me that the U.S. at the moment is one of the main worldwide tax haven for non U.S. national / companies.
Seamus