As the countdown to the June 23 referendum begins, the "Remain" and "Leave" camps are ramping up their campaigning, with latest polls showing an almost neck-and-neck fight.

Hulking campaign buses carrying smooth-talking politicians have started trundling across the country, while smiling volunteers fan out on foot, knocking on doors and giving out pamphlets. Their mission: to sell Britons a vision of why being a part of the European Union is good or bad for them.

While most polls are showing the "Remain" camp to be a notch ahead, a not insignificant 15 per cent comprising undecided voters could sway the verdict either way.

"It's really hard to decide, because staying in seems like a sensible economic choice. But we're also giving so much money to Brussels, which could be better spent in this country, on National Health Service (NHS), for instance," said yoga teacher Julia Holmes, 32, who is undecided.

The rhetoric of the "Leave" campaign, fronted by colourful former London mayor Boris Johnson, has exactly been to use the NHS to bait voters, telling them the £350 million (S$701.6 million) - ­ a disputed figure - Britain sends to Brussels a week could go to save the crippling national healthcare system instead.

Last week, he got placard-waving supporters in the English town of Stafford all worked up when he attacked the EU's seemingly strange laws that Britain has to abide by and asked Britons to "take control".

"It is absurd that we are told you cannot sell bananas in bunches of more than two or three," he bellowed to applause. But critics were quick to accuse him of "making it up as he goes along".

The "Remain" camp led by Prime Minister David Cameron has been using the economic argument to persuade voters.

Come June 23, voters might have been convinced by the numerous warnings about an imminent Brexit disaster. Or, they might have been sold by "Boris' bananas".