In the following provisions a "members' superannuation scheme" means any scheme or arrangement made by or on behalf of a trade union (including a scheme or arrangement shown in the rules of the union) in so far as it provides—
for benefits to be paid by way of pension (including any widows' , widowers', surviving civil partners' or children's pensions or dependants' pensions) to or in respect of members or former members of the trade union, and
for those benefits to be so paid either out of the funds of the union or under an insurance scheme maintained out of those funds.
A trade union shall not maintain a members' superannuation scheme unless it maintains a separate fund for the payment of benefits in accordance with the scheme.