Image copyright PA Image caption As a voter, getting a few leaflets through the door could be the least of your worries

Is there such a thing as campaign etiquette? How should you behave when a politician knocks on your door over the coming weeks?

In the 1965 television satire, Vote Vote for Nigel Barton, the eponymous Labour candidate and his agent Jack Hay get a nasty surprise when they go canvassing for votes.

Convinced that the occupants of one house are hiding from them, Hay repeatedly knocks on the door, ignoring Barton's plea that they should be "left in peace".

After a while, a young girl emerges to tell them politely that "my mummy says not today thanks very much".

When this doesn't succeed in deterring them, the family dog appears and chases the hapless pair down an alleyway, scattering their leaflets everywhere.

Fifty years on, this portrayal of a naive candidate and his manipulative sidekick, by playwright Dennis Potter, has dated a little but many of its observations on electioneering are still pertinent.

Image copyright AP Image caption Labour candidates are expected to have four million conversations

Unless you are a party activist or sympathiser, the chances are as a member of the public you will rarely come into contact with a politician.

Having one suddenly turn up on your doorstep is likely to be about as welcome as a cold shower on a winter morning.

In recent years, door-to-door canvassing may have lessened in importance a bit with much of the hard grind done over the phone, the internet and via social media.

But all parties know that face-to-face encounters can still be the most effective method of garnering votes.

Bath towel

Labour alone is aiming to speak to four million voters on doorsteps up and down the country - almost half the eight million people who voted for the party in 2010.

That's an awful lot of shoe leather to be worn before 7 May.

With fewer constituencies than ever the preserve of a single party, and with UKIP and the Greens challenging like never before in some parts of the country, people can expect more visitors than ever before.

So how should unsuspecting residents deal with the influx of rosette-wearing, leaflet-brandishing candidates and their teams?

Image copyright PA Image caption So who will you be voting for in 18 years time?

The list of what not to do when a politician appears on your doorstep can stretch the imagination, as Gyles Brandreth, the TV/radio celebrity and former Conservative MP, can attest to.

During one of his campaigns, he recalls a woman "who came to the door dressed only in her bath towel and kept letting it slip".

Anna Post, one of the leading etiquette experts in the US, says answering the door in a state of undress is not recommended as are other things which hint at less than 100% attention "such as having your phone pressed to your ear while baking brownies".

Obviously, your reaction to having a stranger in your midst may depend on whether you are considering voting for the party they represent.

With the sophisticated database mining and direct marketing tools at their disposal, parties already know where many of their supporters live.

Image caption Election agents that won't taken no for an answer are largely a thing of the past

As so much effort is put into getting out the vote, the chances are you are more likely to get a visit from a party who already thinks they can depend on your support or hope to.

While some candidates may dream of talking doubters around or converting critics to their cause, transforming political loyalties in a matter of minutes - the time allotted to most doorstep visits in a hectic campaign schedule - is fairly unrealistic.

So the likelihood is that the person who knocks on your door is someone you will be relatively well-disposed to. So what do you do next?

'Just say no'

Wish them well in their efforts and express the sincere hope they will be successful? Or seize the once-in-a political lifetime opportunity to pin them down on that thing that has been bugging you for years.

Anna Post, who advises on etiquette at the Emily Post Institute, says it is sensible to have a clear idea of what you want to talk about before opening a conversation.

"There are a lot of people who end up having a conversation because they don't want to be rude or perceived to be rude or to say no to people," she says. "It is OK to say no."

Image copyright Reuters Image caption You are still more likely to get a call from a politician than see them face-to-face

For anyone who feels uncomfortable about putting a politician on the spot, she suggests coming up with three things that might inspire you to feel better about politics.

For those who want to probe a little deeper, how about taking the conversation a little bit further over a pot of tea?

Allowing any politician into your home is not for the faint-hearted.

When this happens, it tends to be the result of either pre-arranged photo opportunities staged by the parties or, as in the case of Gordon Brown's hour-long drop-in on Gillian Duffy in 2010, rushed exercises in damage limitation.

'Be polite'

While the majority of doorstep visits will be perfectly amicable, it is inevitable the odd one will be adversarial - most likely when a candidate is campaigning in a ward that is predominately supportive but where there are pockets of opposition.

Although it may be tempting to berate a politician and to "send him homeward tae think again", Anna Post says this is not "very fruitful".

"It is OK to say what you want but you need to do it politely and not slam the door in someone's face," says Anna Post, who once worked for a US senator and who wrote a book on what Barack Obama could teach people about civility.

Gillian Duffy's explosive encounter with Gordon Brown may have been an object lesson to politicians about how not to deal with a random encounter on the campaign trail.

There are plenty of other examples of other recent transgressions, including the moment, in 2001, when Labour's John Prescott got into a fist fight with an egg-throwing bystander.

Speaking of that John Prescott punch, it is not just the voters who can stretch the spirit of campaign etiquette in the hurly burly of an election.

"John Prescott's mother was a constituent of mine," recalls Gyles Brandreth. "When John was due to visit one weekend I persuaded her to put one of my posters in her window."