Phill,
I had the same, with the only exception that my house didn't exist!
My house was being built and I guess that the address had been registered enabling the contractors working on behalf of TV licencing to send out bulk letter to addresses that weren't shown as having TV licences. When the house was completed I received all of the post that had been stored over the past few months,consisting of mostly threatening letter from these folks. It also stated that enforcement officers had been around but couldn't get an answer during periods when all they would have seen was a field.
I carried on getting the letters after transferring my TV licence and eventually after tiring of speaking to people and writing a couple of letters, I wrote to the local MP. I'm slightly embarrassed of wasting someone's time like this but it had the desired effect. I had several letters of a apology from TV licencing and haven't been bothered since.
Chris