Thousands of British police officers planned to join striking border officials and healthcare workers Thursday in a protest against wage caps, pension reforms and other austerity measures. Unions predicted some 400,000 public sector workers would walk out, a smaller protest than in November when Britain saw the biggest strike in years, but a significant show of public discontent just after Prime Minister David Cameron's government took a drubbing at local elections. The rare sight of some 20,000 off-duty police officers marching through London will be particularly embarrassing for Cameron, whose centre-right Conservatives pride themselves on being the party of law and order. “Prime Minister, actions speak louder than words,” the Police Federation union said in full-page adverts published in several national newspapers on Thursday. “Police officers feel strongly that the government cutting the police budget by 20 percent, privatizing core policing roles and pushing ahead with its ill-considered police reforms could jeopardize public safety,” the union said. The Conservatives and their junior Liberal Democrat partners have vowed to press ahead with unpopular austerity plans despite both parties suffering badly in local council elections last week amid discontent that the country had fallen back into recession after two years of deep spending cuts. Public hostility to austerity has hit governments across the European Union, with French President Nicolas Sarkozy ousted by Socialist Francois Hollande who promised a gentler approach on debt reduction, and Greece in political crisis after voters deserted the main parties. “(Finance minister) George Osborne's austerity plans are beginning to sicken everyone,” said Gail Cartmail, assistant general secretary of Britain's largest union, Unite. Nick Herbert, the minister in charge of policing, defended the government's actions. “It's very important that tough decisions are taken to deal with the deficit and the police service, police officers, I'm afraid, can't be exempted from that. I really don't think that would be fair,” Herbert told Sky News. Police officers have been legally barred from taking industrial action since the 1990s. The Police Federation, which represents 135,000 low ranking officers in England and Wales, said Thursday's action could be larger than the biggest police protest staged in Britain, in 2008, over a pay row with the then Labor government.