The story behind classic election images

Winston Churchill campaigns from the balcony of the Red Lion Hotel, High Wycombe, 25 June 1945

Through the stories behind five iconic images, Election Snapshots brings photographers and political insiders together to chart how election campaigning has developed and changed in the past 70 years.

Campaigning in 1945 seems a world away from today. It's not only the sight of a prime minister standing precariously on an unprotected balcony 20ft (6m) up in the air, but also the sight of him appearing in person, before a huge crowd of the general public, supporters of all parties and none.

This is how the leader who saw Britain through World War Two tried to translate the admiration he received for that achievement into domestic political success.

It's a far cry from the staged rallies and bussed-in crowds of party members which modern election campaigns now seem to feature.

Margaret Thatcher, inside No 10 on election night, 9 June 1983

This intimate photograph of Margaret Thatcher pioneered how political leaders might reveal their private moments to win the support of the electorate.

As Britain's first female Prime Minister, Margaret Thatcher changed many of the conventions about how politicians should be presented. Images of her would both make use of, and seek to compensate for, her femininity. She often featured alone in a landscape - to emphasise her leadership and prime position at the head of government.

In this picture, Lady Thatcher's mouth is slightly tense, ascribed by photographer Herbie Knott to the news she'd received that evening about an extra-marital affair conducted by one of her most trusted ministers, Cecil Parkinson.

Cherie Blair answers her front door on the morning of Labour's 1997 general election victory

For many the defining image of Labour's landslide victory in 1997 was Cherie Blair answering her own front door the morning after the poll.

Oblivious to her own appearance, Cherie was yet to understand the intense media scrutiny which her family would experience for as long as her husband remained prime minister.

The photo offers a glimpse of how all aspects of politicians' lives were now becoming part of the electoral battle, and how the worlds of celebrity and politics were about to merge, as images would be used in a new way to present the nation's political elite.

Charles Kennedy campaigns inside an operating theatre, Southampton, 2001

Politicians push the boundaries to convince voters they understand and share the concerns we all have in our daily lives.

Hospital visits are a staple, but never has a party leader found themselves at a campaign photo-op inside an operating theatre whilst an operation actually takes place. Not until Lib Dem leader Charles Kennedy visited Southampton General Hospital in May 2001.

Having observed the heart operation carried out under local anaesthetic whilst the patient was conscious, Kennedy stepped forward to meet the man - desperately hoping that his own strong fear of the sight of blood would not cause him to faint on the spot and provide the press with an even more dramatic photo.

Gordon Brown meets Gillian Duffy, Rochdale, 28 April 2010

Gaffes can define elections, and in 2010 the encounter between then-PM Gordon Brown and Rochdale pensioner Gillian Duffy threatened to derail Labour's campaign.

Senior politicians meeting ordinary members of the public can be a necessary hazard for every political strategist, and on this occasion, an exchange between Mr Brown and Mrs Duffy about immigration led to an extraordinary turn of events which has haunted the Labour Party ever since.

Photographer Jeff Mitchell remembers how this photo only became significant once Mr Brown's off-camera remark about Mrs Duffy being a 'bigot' was picked up by a microphone on his lapel.

David Muir, Brown's Director of Political Strategy at the time, tried to remain as calm as possible and work a way out of the crisis by supporting Brown's return, to apologise personally to Mrs Duffy in her home.

Election Snapshots will be broadcast every weekday from Monday 20 April on BBC Radio 4 at 12:00 BST and will be available afterwards online.

It features interviews with Cherie Blair, Lord Bell, close confidante and adviser to Lady Thatcher, and photographers Herbie Knott, Martin Argles and Jeff Mitchell. The series examines how the tensions between politicians and the media play out under the intense pressure of campaigning to win. The story behind each photograph illuminates how campaigning has changed since 1945, and what we might expect from this year's general election.