The law requires at least one third of the trustees of any occupational pension scheme to be member-nominated trustees (although the statutory public sector schemes are not covered by this rule.) Some schemes do better than this, and some have 50/50 member/employer representation with an independent Chair.
Different methods are used for appointing the member trustees as what makes sense in a smaller scheme with only one workplace might not work for a large company based on a number of sites.
Elections are sometimes used, or there may be some other form of selection process. All trustees, whether appointed by the employer or elected by the members, have the same legal duty to act in scheme members' interests.
Member trustees should not be seen as representatives or delegates of the members as they must comply with their legal duty as trustees.