What does it mean to have a direct or indirect representative for customs clearance in the UK?

When goods cross a border, customs formalities need to be completed. The trader has the option to complete the formalities themselves, or engage someone else to do this for them. Generally, traders find someone, such as a customs agent, to complete the formalities for them. In this case, the customs agent would act as either a direct or an indirect representative. This article explains the difference between these two types of representations and what the responsibilities and liabilities are for both the trader and the customs agent.