As they come to the final week in the Newark by-election, the blue buns are out in front. The purple buns are tucked in behind in second place, with the red buns in third.

There are eleven runners in this race, each represented by a different coloured bun in Les Flowerdew’s bakery in London Road, Newark. His customers are encouraged to buy whichever bun represents the party they intend to support in the by-election on Thursday 5 June, and at present the Tories are ahead of UKIP.

As Lord Ashcroft would remind us, this is a snapshot, not a prediction. But it is already clear that Mr Flowerdew has emerged as one of the winners of the contest. For on Wednesday of last week, David Cameron and Boris Johnson arrived with a retinue of assorted journalists in the fine old market place in the middle of Newark where Mr Flowerdew twice a week has a stall.

The Prime Minister bought, and shared with the Mayor of London and with Robert Jenrick, the Conservative candidate in Newark, a piece of Mr Flowerdew’s Rocky Road biscuit cake. According to the baker, the effect on business has been dramatic: “It’s gone through the roof, believe it or not. Sales have trebled.”

And how did he find Mr Cameron and Mr Johnson? “They were very good,” he said. “Believe it or not, we didn’t speak about politics. We spoke about making bread.”

Here we have, in a nutshell, the Conservative campaign. It is intended to be optimistic and unpolitical, and to show that the Tories are human beings: a point many voters have for a long time been unable to accept.

According to Mr Flowerdew, to whom I talked yesterday morning as the rain spattered down on the awning over his stall, his family escaped from France at the time of the French Revolution, and his name is an English version of “Fleur-de-lis”. Baking, he says, is in his blood. So without wishing to place an excessive weight of interpretation on this encounter, I would suggest he is an example of how this country has been enriched by the arrival of immigrants who become British.

A few yards away, a cluster of purple and yellow umbrellas had appeared outside Newark’s splendid Town Hall, designed in 1776 by John Carr of York. Roger Helmer, the UKIP candidate, had arrived in the market place.

Mr Helmer, who was a Conservative MEP from 1999 to 2012 before switching to UKIP, was giving an interview to The New York Times. He was wearing a blazer, sports a white moustache which curves in a distinctive way round the ends of his mouth, and is 70 years old. His manner is reminiscent of Basil Fawlty: it combines friendliness with the seething anger of a man who knows himself to be talking perfect sense, yet at every turn finds himself misunderstood.

In Mr Helmer’s pronouncements over the years on subjects such as rape, homophobia and the desirability of shooting rioters, there are various things which people have tried to use against him. But part of UKIP’s appeal is that its candidates are less inhibited, and speak more like the man in the pub, than those of other parties.

“I’m not a metropolitan liberal,” Mr Helmer explained to The New York Times. “I’m not an Ed Miliband and I’m certainly not a David Cameron.”

According to Mr Helmer, the biggest issue of the campaign is immigration. He claimed that “native English people who speak English are unable to get jobs in factories because they don’t speak Polish”. In his view, the by-election is a two-horse race and UKIP are “in with a chance”.

One of the enjoyable and rather surreal aspects of a by-election is the way one comes across well-known people in out-of-the-way places. At noon yesterday, the Foreign Secretary, William Hague, appeared in The Maltsters, a cul-de-sac of modern brick houses, some with half-hearted bits of half-timbering, just off Farndon Road, which stretches south-west of Newark along the River Trent.

No corner of this constituency, which covers a tract of Nottinghamshire running from the Vale of Belvoir in the south almost to Yorkshire in the north, is at present immune to visits from Cabinet ministers. George Osborne, Michael Gove, Philip Hammond and Ken Clarke are among the better-known ones to have been spotted in recent days.

This was the Foreign Secretary’s third visit. About 20 minutes before he arrived, four Conservative activists arrived and began distributing leaflets up and down The Maltsters. Two of them, who introduced themselves in a friendly way as Fiona and Robin Hodgson, turned out to be members of the House of Lords. The Conservative Party has flung every minister, MP, candidate, activist and aristocrat it can lay its hands on into this battle.

The Maltsters was sunk in noonday calm. A man came out of his house, looked with annoyance at the way some cars were parked, and said: “Well here’s an example of Tory arrogance.” He refused to take the point that the cars belonged to members of the press.

Most other people seemed pleased to see Mr Hague, at whose side trotted the younger, shorter, chunkier, cheerful but not very communicative Mr Jenrick. When a young mother had her hands full carrying her sleeping child into the house, the Foreign Secretary at once got the point: “OK, we’ll leave you to it.” A journalist asked Mr Hague how the campaign was going. He replied: “We’ve got a very good candidate. He’s doing very well. But we take nothing for granted. It’s a serious election and we treat it very seriously.”

At last we got a word with Mr Jenrick. He spoke about the importance of local issues, including slow response times by ambulances. This is an issue Mr Cameron has taken up on his visits to Newark, and something a Conservative voter had mentioned to me in tones of horror: she fears her husband, who has already had a stroke, will die when he has another one because he will not get to hospital in time.

Mr Jenrick, who is 32, seemed reassuringly dull. He fought Newcastle-under-Lyme in 2010 and was adopted as the candidate in Newark about six months ago, at which point it was expected his scandal-afflicted Tory predecessor, Patrick Mercer, would just stand down at the general election. When someone suggested to Mr Jenrick that he had not expected to have to fight a by-election, he agreed, but added: “It’s a great opportunity in certain respects.”

He went to Wolverhampton Grammar School and read history at St John’s College, Cambridge, before becoming a lawyer. When asked who his political hero is, he became more animated, and vouchsafed that he is writing a book about the English Civil War, in which Newark played a prominent role: it was a royalist stronghold which was three times besieged unsuccessfully by the parliamentarians. The first siege was raised by no less a figure than Prince Rupert, the most dashing royalist of them all.

And Prince Rupert turns out to be Mr Jenrick’s hero. Beneath that somewhat impassive exterior perhaps there beats the heart of a true cavalier.

In 1832, one of the most amazing politicians in British history fought this seat. William Gladstone, who was only 22 at the time, became the candidate in Newark at the invitation of the Duke of Newcastle, who despite the passing of the Great Reform Bill still had a preponderant influence here.

The Duke’s son, Lord Lincoln, was a friend of Gladstone, and recommended him after hearing him denounce the Reform Bill in a powerful speech at Oxford: Gladstone, when mocked by Disraeli and others for having been at this point not just a Tory but an arch-reactionary, admitted that “there was to my eyes an element of the anti-Christ in the Reform Act”.

In Newark, he loved the campaign, though stones were thrown at him which missed him by only “twelve inches” and he had to be “most powerfully escorted” by his supporters to the Clinton Arms, an old coaching inn on one side of the market place. Gladstone topped the poll. To his mother he wrote: “Such a stirring succession of outward circumstances as have surrounded me – such a wonderful medley of motives as my canvas has introduced me to – and such a rapid variety of thoughts as these have combined to produce – may be commonplace to experienced politicians, but to me and my habits…they bear the aspect of enchantment.”

In 2010, Mr Mercer polled 27,590 votes, Labour 11,438, the Liberal Democrats 10,246 and UKIP 1,954. I saw nothing of the Lib Dems yesterday, and assume their vote will collapse, but where it will go is hard to predict. The turnout is likewise uncertain. It did not strike me that enough people in Newark are feeling so precarious or desperate that it should be regarded as prime UKIP territory. There is a respectability about the place which leads at least some of its inhabitants to favour the Tories.

Mr Hague kept repeating: “We take nothing and nobody for granted.” It is the only spirit in which to fight this election. For the Tories to lose it after putting in so much effort would be a body blow. To win it might put the party on course for victory in May 2015.

As I sat drinking a cup of tea at Newark North Gate station, who should I see racing along the platform, having just got off the London train, but the urgent figure of Ed Miliband. For a moment, I contemplated pursuing him, but then I decided to finish my tea. There is only so much excitement one can cope with in one day.