Where directors (including their connected persons, related trusts and companies controlled by such directors, connected persons and related trusts) or shareholders or groups of shareholders acting collectively holding effective control, whether represented on the board or not, sell shares to a purchaser, as a result of which the purchaser is required to make an offer under TMA-3.1 (Mandatory Offer), the vendors must ensure that as a condition of the sale the purchaser undertakes his obligations in accordance with TMA-3.1 .