All Members of Parliament are expected to uphold the highest standards of probity and conduct.
To this end they must declare their financial – and some other – interests in the Register of Members’ Interests, and they must abide by a the Code of Conduct of Members of Parliament.
The Register of Members Interests includes details of the staff or family members that an MP employs; any significant shareholdings or property income that they possess; gifts and donations that they have received; and details of the outside employment or Directorships that they undertake.
At the start of a new Parliament, Members of Parliament have one month in which to make their first registration in the Register of Members Interests. After that, MPs must register within 28 days any interest which someone might reasonably consider to influence their actions or words in Parliament.
The system of standards is ultimately the responsibility of the House of Commons Committee on Standards and Privileges.
It oversees the work of the Parliamentary Commissioner for Standards who maintains and monitors the register and the code and advises the committee on it. The commissioner also receives and investigates complaints against MPs on which it reports to the committee.
The committee may then make recommendations to the House on action to be taken against an erring member.
The latest copy of the Register of Members Interests can be found here.