208. Membership to be voluntary.

Subject to prescribed exceptions, membership of a personal or an occupational pension scheme is to be voluntary and any term of a contract of service1 or any rule of a personal or occupational pension scheme to the effect that an employed earner2 must be a member of a particular occupational pension scheme or one or other of a number of particular occupational pension schemes, is void3. This rule does not apply, however, during any period when that scheme is, or those schemes are, so framed that in relation to that period: