Believe it or not there are still people out there who do not have a bank account, for various reasons.
Anyone who is receipt of benefits (child benefit included) or a state pension, whether they have a bank account or not can elect to collect their money at a Post Office. They no longer have 'pension books' but have a chip and pin card. I believe that these can also be used in Post Office cash machines aswell as at the counter.
If you would like yours paid this way then you contact the agency who pays you the money and they will send you a form to take into a Post Office to arrange for you to collect a card.