If you contract with a limited liability company be sure you record its correct name. For example you may contract with John Smith & Brown Limited. It is perfectly permissible for John Smith & Brown Limited to have a trading name totally unrelated to its registered name. For example it could trade as "Country Catering". It is important that you identify with whom you are trading as judgment against Country Catering will be totally ineffective as that entity does not legally exist. Proper investigations should reveal the legal identity of your customer and this is an extremely important function which a business' credit control must perform accurately and expeditiously.
Similarly a partnership or sole trader may trade in their own names or in a business descriptive name.