Married Mans allowance (and Mortgage Releif MIRAS) was abolished in 2000.
AFAIK there are no benefits to being married.
There are no government benefits to being a loving family whether married or not.
The removal of married mans allowance and MIRAS means that both parents have to work in order to feed and house their families. This is being increased by the provision of child care from lower ages (3 years is it?)
IMO The breaking up of family life (married or otherwise) by financial policy has lead to the current increase in gang culture as there are no stable roll models available.