Set up 95 years ago to stop cattle being pole-axed to death, the association has become a kind of benevolent Grim Reaper to livestock.
It believes that if an animal is to end up on the kitchen table, its journey there should be as painless as possible, so it promotes a "positive, rational approach" to slaughter.
One of its biggest lobbying successes came with the 1933 Slaughter of Animals Act, which made the humane stunner compulsory and outlawed bludgeoning livestock to death.
These days the charity focuses on issues such as abattoir conditions and horse passports. It offers £1,000 grants for humane slaughter projects in memory of the late Dorothy Sidley, its general secretary for 48 years.
Grants have funded research into issues such as the effects of head restraints on cattle.
The charity has no celebrity supporters, but it employs a full-time slaughter specialist, who gives demonstrations in abattoirs all over the world.