If you have any record of the conversation, an email or written correspondence, take that to a local real estate attorney and ask what they recommend. If the UK agent is licensed in the US or is local and practicing without a license you may have a course of action against them. Only an attorney can tell you for certain. Many will give you an initial consultation for free or a low flat fee. Without proof it will come down to your word against theirs.
You did not go through an escrow company or obtain title insurance or you would have known about the delinquent taxes and, probably, about the imminent foreclosure.
You say you bought a house but you probably do not own the property since the holder of the loan would not release the deed to you unless the loan was paid off.
You have been victimized by your UK agent. You should seek legal advice to determine if you can obtain any redress.
Investors should always require proof of recordings, tax records, title documents, etc to ensure that a property can be safely transferred.
It's not illegal if someone buys without this proof, but certainly not in their best interest.
It is however, unethical. If this info was given by a licensed US agent, you have recourse.
Otherwise there are several legal outfits that are beginning to help overseas investors who have suffered fraud.
Try Heidi Sharp
Burgess and Sharp
I can't promise she'll take your case but she will try to help.
Did you have a loan on the purchase? If so, a lender would require Title Insurance to protect you from this happening. Contact the Title Insurance Company first thing tomorrow. There should be no cost to you as you already paid for this with the policy.