The worst night of the Brown Dog riots in London, when 1,000 medical students clash with 400 police officers over the existence of a memorial for animals that have been vivisected.

The Brown Dog affair was a political controversy about vivisection that raged in Britain from 1903 until 1910. It involved the infiltration by Swedish feminists of University of London medical lectures; pitched battles between medical students and the police; police protection for the statue of a dog; a libel trial at the Royal Courts of Justice; and the establishment of a Royal Commission to investigate the use of animals in experiments. The affair became a cause célèbre that divided the country.The controversy was triggered by allegations that, in February 1903, William Bayliss of the Department of Physiology at University College London performed an illegal vivisection, before an audience of 60 medical students, on a brown terrier dog—adequately anaesthetized, according to Bayliss and his team; conscious and struggling, according to the Swedish activists. The procedure was condemned as cruel and unlawful by the National Anti-Vivisection Society. Outraged by the assault on his reputation, Bayliss, whose research on dogs led to the discovery of hormones, sued for libel and won.Anti-vivisectionists commissioned a bronze statue of the dog as a memorial, unveiled on the Latchmere Recreation Ground in Battersea in 1906, but medical students were angered by its provocative plaque—"Men and women of England, how long shall these Things be?"—leading to frequent vandalism of the memorial and the need for a 24-hour police guard against the so-called anti-doggers. On 10 December 1907, hundreds of medical students marched through central London waving effigies of the brown dog on sticks, clashing with suffragettes, trade unionists and 300 police officers, one of a series of battles known as the Brown Dog riots.In March 1910, tired of the controversy, Battersea Council sent four workers accompanied by 120 police officers to remove the statue under cover of darkness, after which it was reportedly melted down by the council's blacksmith, despite a 20,000-strong petition in its favour. A new statue of the brown dog, commissioned by anti-vivisection groups, was erected in Battersea Park in 1985.On 6 September 2021, the 115th anniversary of when the original statue was unveiled, a new campaign was launched by author Paula S. Owen to recast the original statue.