The Dog Barons
All of London's dogs are owned by the same company. Amalgamated Canine Industries was founded when the dog population of the city was nationalised under the Attlee government in 1948, and its holdings were leased back to the pooches' former owners. Since then, this company has, in various forms, regulated all dog activity in the capital.
However, it was not always successful. Inefficiencies and strikes in the late 1970s plagued ACI, and ultimately led to some dogs going as much as three days without walkies. Hampstead Heath was littered with unreturned sticks, and the Minister for Employment struck out at some of those involved, claiming "I have found many to be not very good boys at all".
In 1987, Thatcher privatised ACI in order to improve its competitiveness, and in 2001 the company rebranded as ProCanis.
On a related topic, it's interesting to note that, although they operate on a freelance basis, the squirrels of St James's Park are unionised. This makes them the third most organised group of animals in London after dogs and wombles. Wombles do not have their own union, but most are members of Unison, the public service union.