The Latest on the British referendum on EU membership (all times local):

8:50 a.m.

Prime Minister David Cameron is taking on a frantic day of campaigning on the eve of vote on whether or not Britain will leave the European Union.

Cameron defended Britain's participation in the 28-nation bloc in a BBC interview Wednesday, arguing that the country benefits from membership and rejected the notion that the institution is moribund.

Cameron says: "We are not shackled to a corpse."

Meanwhile, the most notable figure in the "leave" campaign, former London Mayor Boris Johnson, has kicked off a whirlwind tour of England as he pushes for a British exit — or Brexit.

Johnson toured Billingsgate Fish Market and urged voters to "believe in our country."

He says "this is a crucial time."

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8:35 a.m.

Leaders of about half of Britain's largest companies have made a last ditch appeal to their employees to vote for remaining in the European Union.

In a letter to the Times on the eve of Thursday's vote, some 1,285 business leaders — include representatives of half of the FTSE 100 businesses — argue that a vote to leave will hurt the British economy.

Similar letters have been released in the course of the acrimonious campaign. But Wednesday's letter is clearly meant to make the 1.75 million people employed by the signatories to think twice about their vote.

"Britain leaving the EU would mean uncertainty for our firms, less trade with Europe and fewer jobs," the letter says.

The companies represented include Barclays, Standard Life and Anglo American.