William Alexander Mackinnon DL JP FRS (2 August 1789 – 30 April 1870) was a British politician and a colonisation commissioner for South Australia.

During the late eighteenth century, a new type of humanitarianism was developed through evangelical piety and romanticised ideology, which advertised the plight of animals.

[23] Founded in London as the Society for the Prevention of Cruelty to Animals by Reverend Arthur Broome and Richard Martin in 1824, the charity was granted Royal status by Queen Victoria in 1840 and became the RSPCA as it is known today.

Humanitarians such as William Alexander Mackinnon were eager to reduce Britain's national association with cruel sports as well as tackling cruelty overseas.

Brian Harrison notes that during the 1836 annual meeting of the Society, Mackinnon took pride in the fact that ‘to Englishmen alone is the credit due, of having been the first to take up the cause of the suffering dumb creation’.

The Society could not promote legislation of Acts of Parliament to protect animals and birds, so instead relied on the prerogative of individual MPs and governments.

This was a momentous step forward as it illegalised the use of public and private spheres for running, baiting or fighting bulls, bears, badgers, dogs and other animals, whether wild or domestic.