A person has three years from date of imjury or date of knowledge whichever is the sooner to make a personal injury claim.
1 year after the event is not uncommon, however depending on what the severity of the injuries are will determine the credibillity of the claim.
Your insurance will still cover you. You would be wise to contact your insurance company advise themn of what has happened but also get them to flag up that you suspect it may be a scam claim.
They should be happy to advise you and take over all correspondence from the claimant and deal with it as if the incident had just occured.