4. A factor underlying the complaints is that in April 1997, the Scheme established an M Plan which gives its members benefits on a defined contribution (dc) basis whereas the C Plan which was already in existence gives its members benefits on a defined benefit (db) basis.

Not all the complaints.   Complaints about pensions-in-payment policy are based on promises made well before this event and extend after the event.   The gap between the promise made and the delivery is crucial, irrespective of the event.