If you receive a letter asking you to confirm your company details we strongly recommend you READ THIS FIRST
The paperwork is headed INDUSTRY AND COMMERCE with a sub heading Register of Business Information looks like this:
Read the small print at the foot and it becomes clear that what you are actually signing is an Order for insertion into a directory style websites at www.united-kingdom-industry-commerce.com and www.europeancityguide.com plus a CDRom - costing Euro 997.00 plus VAT per edition. If you sign it and send it back you will be issued an invoice plus a series of legal court orders for the outstanding amount plus interest should you not pay.
A quick Google for European City Guide and you will see many complaints about their trading practice including articles from the UKs Office of Fair Trading reporting that this company in Spain has been fined and shut down several times.