General selection: The best pictures from the UK's parliamentary poll
Boris Johnson said he thought people should serve full prison sentences.
The left-wing Labour party, in contrast to the Conservatives, is de-emphasising Brexit and concentrating instead on domestic issues in its newly-released manifesto.
Watson had long been a thorn in the side for the Labour left.
UK Prime Minister Boris Johnson mocked Labour leader Jeremy Corbyn on Wednesday, comparing his refusal to hold elections thus far to the precepts of late Cuban dictator Fidel Castro.
Although under fire from all sides over Brexit, Britain's ruling Conservatives under Prime Minister Boris Johnson still lead in the opinion polls.
British opposition Labour leader Jeremy Corbyn won support for his Brexit strategy on Monday, fighting off a challenge by members who wanted him to immediately back remaining in the European Union before any election.