The Milk Marketing Board was an agency of the British government.
The Board bought all of the milk in England and Wales from dairy farmers and passed it on to be processed and sold. This way small farmers always got a fair price, because no big producer could sell their milk more cheaply.
The Board was first set up in 1933. In 1933 and 1934 three other boards were set up for Scotland and one for Northern Ireland in 1955.
From 1958 until it was abolished the Milk Marketing Board sponsored (paid money for) the Tour of Britain bicycle race, which was called "The Milk Race".
uk/foodrin/milk/pdf/historyofmmbs.pdf History of the Milk Marketing Boards