Before appointment, the organisation should complete due diligence to make sure the new board member is appointable. The Insolvency service holds a list of undischarged bankrupts. The Charity Commission has a list of people who are barred from being trustees. An organisation’s constitution may include qualifications that a new trustee must hold (for example, a condition that a new board member must be over 18 years old). If so, you may need to keep evidence on file that the relevant conditions are fulfilled. New anti-money laundering rules will apply soon, which will oblige all companies to check the ID of new directors, and the Charity Commission is creating personal accounts for all trustees so that their details are kept up to date.
Once formal approval of a new board member has been given by the board notification has to be made to the relevant regulator, for instance Companies House and/or the Charity Commission. Charity trustees should also complete a declaration of eligibility, confirming their eligibility to be a trustee, see https://www.gov.uk/government/...
The declaration may also include a personal data privacy statement, so that the organisation can share contact details of the new trustee with other board members. Any potential conflicts of interest can also be recorded.
A template for a charity trustee declaration of eligibility form appears here
Every company and CIO must (and other organisations should) have registers of their board members.