Being a director can be a risky business
Most company directors will hopefully be well aware of the responsibilities of their position, but not all will be aware they face unlimited personal liability arising from the decisions and actions taken in running the business. Limited liability only applies to the shareholders whereas directors can face sanctions that could involve the seizure of personal assets.
As a director you are legally required to act with care, in good faith and within the law. You have a duty to act in the best interests of the company, including a responsibility to ensure that other directors and officers do likewise.
Claims can come from many sources as I mention later, but as an example there are over 200 ways a director can incur fines or penalties under the 2006 Companies Act alone and that is without the seemingly constant barrage of recent regulations from Europe.