You don't need a registered trademark to sue for name theft. UK common law protects trading names through "passing off" if you can prove these 3 elements in court.
Element 1: Goodwill
Reputation with customers. They associate the name with your business specifically.
Element 2: Misrepresentation
Competitor uses confusingly similar name. Customers believe it's you or associated with you.
Proving Customer Confusion
Surveys, misdirected mail, phone calls intended for them. Document everything.
Element 3: Damage
Lost sales, reputation harm, customer confusion. Quantify in pounds.
Evidence You Need
Sales records, customer testimonials, marketing materials, media coverage. Build this from day one.
Warning: Passing off cases cost £50,000-200,000 in legal fees. Registered trademarks cost £170-400. Prevention is cheaper.
Generic Names Can't Be Trademarked
If you want legal protection and a name competitors can't copy, make it distinctive from day one. Generic names fail both trademark AND passing off protection.