Can a company simply ignore its own constitution?

A company's constitution binds the company, its board and its shareholders under the Companies Act 1993, so directors must comply with it when exercising their powers. If a decision contravenes the constitution, it may be invalid or open to challenge, depending on the nature of the breach and the rights of outsiders who dealt with the company in good faith. As a shareholder, you can ask the board to explain the basis for its decision, request relevant records and, if necessary, apply to the High Court for an order restraining the company or directors from acting contrary to the constitution or requiring them to comply. Written legal advice about which part of the constitution is engaged will help, and any wording in a shareholders' agreement should be considered alongside it.