Under the Pensions Act 1995, trustees must have a clear 'audit trail' in place as regards the professional advisers they use, including their legal advisers. In part, the Act seeks to ensure that any conflicts of interest that the advisers have are flagged up with the trustees (for example, if the advisers also advise the sponsoring employer of the scheme on issues of direct concern to the trustees).
We have a standard appointment notice that the trustees can use (if appointing us) to satisfy the Act's record keeping requirements. It can be downloaded from the link below.