The party leaders will be inescapable until 8 June as they are photographed non-stop on the campaign trail, kissing babies and knocking on doors. But who are the strategists plotting behind the scenes?

Sir Lynton Crosby

The strategist cut his teeth working for the right-wing Liberal party in his native Australia, helping John Howard to successive victories between 1996 and 2004.

Back then he carried a business card bearing the words of the Ancient Greek philosopher Solon: "When you give advice seek to help, not to please."

This has certainly been true of his career on the British political scene, which began when he became one of the top advisers to Conservative leader Michael Howard in the 2005 election campaign.

The campaign was ultimately unsuccessful, but it bore the hallmarks of his approach, which helped Boris Johnson to victory as London mayor in 2008 and 2012.

Image copyright Getty Images Image caption Boris Johnson's mayoral election campaigns were masterminded by Crosby

He placed an emphasis on targeting strategic seats - in the case of the mayoral elections, prioritising suburban London over Labour's traditional inner-city strongholds in what became known as "the doughnut strategy".

He earned a reputation for pushing subliminal messages on issues such as immigration, decried by opponents as "dog-whistle" politics.

For Michael Howard, this found expression in the slogan, "Are you thinking what we're thinking?"

Image copyright Alamy

He joined Conservative HQ as a part-time consultant at the beginning of 2012, stepping up his involvement before the 2015 general election.

During that period, Labour claimed his background as a lobbyist for tobacco giant Philip Morris was influencing the government's public health policies, which he denied.

He was also criticised by some in the Conservative Party who felt he was too right-wing to appeal to more moderate British voters, but the then chairman Grant Shapps described him as "a serious campaigner" with "the kind of focus that's required".

His services come with a hefty price tag, it's been suggested. Mr Johnson advised David Cameron to "break the piggy bank" to get him on board for the 2015 general election.

It was worth it, in the eyes of many Conservatives, as he helped deliver their unexpected Commons majority two years ago.

He was given a knighthood in the 2016 New Year honours, a move condemned by Labour as "outrageous".

Image copyright PA Image caption Sir Lynton was knighted in 2016

He declined an offer of £2m to work for one of the No campaigns in the EU referendum - but he's now back on the scene running the Conservative Party's election campaign with his agency CrosbyTextor.

His presence is likely to be as controversial as ever, with some linking his appointment to the departure of other members of Theresa May's staff. For others, he remains the "alpha male" the party needs.

The party's relentless focus on one or two simple slogans - "strong and stable leadership" being the most obvious one - coupled with robust attacks on the character of its opponent, in this case Jeremy Corbyn, are hallmarks of the no-holds-barred Crosby campaigning style.

Who else?

Image copyright PA Image caption Nick Timothy and Fiona Hill

Just as important is Lord Gilbert, a stalwart of Conservative central office, who is running a tightly controlled strategy with its sights on taking seats the Conservatives have not won for years and Theresa May at its centre. He's seen as returning the party to an older and more traditional version of itself after the perceived slick "posh boy" image of David Cameron and George Osborne.

Former campaign manager for Barack Obama Jim Messina and his team have returned after an advisory role with the Conservatives in 2015. Mrs May's trusted lieutenants Fiona Hill and Nick Timothy are key figures in shaping how the prime minister approaches the campaign, while Tom Edmonds and Craig Elder are leading the way on digital campaigning, as they did in 2015.

Seumas Milne

In some ways, Labour's director of communications could not be more different from Sir Lynton, with his roots firmly in the British establishment.

His father was the former BBC director general Alasdair Milne, and he attended Winchester College and Balliol College, Oxford before going into journalism.

He started out on a small Communist-backed paper, Straight Left, and spent three years at The Economist before joining the Guardian in 1984.

He wrote extensively on industrial issues for the Guardian, being promoted to labour editor and later comment editor, and represented the paper in the National Union of Journalists.

His tenure as comment editor in the early 2000s grated with some of his fellow journalists, with colleagues complaining he was too ready to defend Hugo Chavez and Vladimir Putin, and that he commissioned too many pieces on Palestine.

Image copyright Alamy

But none of that prepared the industry for the announcement in late 2015 that he would take a "leave of absence" to work for the newly elected leader of the Labour Party, Jeremy Corbyn.

He remained officially on staff until January 2017, a source of concern for some at the Guardian, who felt it might inhibit criticism of the Labour leader.

Like Sir Lynton, he has proved to be a divisive choice as strategist.

There have been numerous criticisms of his past opinions including allegations of justifying Russian actions in Ukraine and for describing the murder of Lee Rigby as not "terrorism in the normal sense of an indiscriminate attack on civilians".

His detractors say he is too far to the left, too dogmatic and unwilling to co-operate with the demands of the 24-hour news cycle. Some have also suggested he appears to exercise too much control over Mr Corbyn at times. Some within the party accused him of "sabotaging" Labour's remain campaign.

Others say he's had to maintain a tough stance to counter "annoying" leaks from sections of the Labour Party who disagree with Mr Corbyn. They praise his calm manner as a welcome change from the bullish style of Labour spin doctors past.

He enjoys the advantage, from his supporters' point of view, of being an experienced journalist as well as being very close politically to the party leader.

Image copyright Getty Images

He's also seen by his allies as a quick and reflective thinker with strong principles, and a compelling writer who's effective at capturing the best of Mr Corbyn.

The recent departure of campaigns director Simon Fletcher from Mr Corbyn's top team has been interpreted by Labour-watchers as a sign of Mr Milne taking a tighter grip on the reins ahead of the election.

And with speculation rife that Mr Corbyn could stay on as leader even if Labour loses - or make way for an ally - Mr Milne may be an important figure in the party for some time to come.

Who else?

Image copyright PA Image caption Andrew Gwynne formerly worked with Ed Balls

Seumas Milne will be aided by deputy Steve Howell, from the PR firm Freshwater, and policy director Andrew Fisher, who wrote the Labour manifesto. In charge of Mr Corbyn's office is former Unison official Karie Murphy, who was caught up in the vote-rigging row at the 2013 Falkirk by-election. The two former MPs running the party's national campaign are Andrew Gwynne, former parliamentary private secretary to Ed Balls, and Ian Lavery, an ex-miner and champion of the trade unions.

Liberal Democrats

Communications consultant James Gurling has been brought back into the party as campaign chief from lobbying firm MHP, having previously chaired the Lib Dem campaigns and communications committee.

He was a press aide to former leader Paddy Ashdown in 1997 and leadership election agent to Charles Kennedy, who was his brother-in-law, as well as a councillor for the Lib Dems in Southwark.

Another returning activist is Phil Reilly, director of communications, a former aide to Nick Clegg as deputy prime minister and devout West Ham fan.

Two other influential figures are Lib Dem leader in the Lords, Lord Newby, who chaired the party's manifesto group, and party leader Tim Farron's chief of staff Ben Williams, who was in charge of the whips' office during the coalition, described by one insider as "the power behind the throne".

SNP

The SNP's campaign manager is MSP Derek Mackay, the party's business convener (chair) and finance secretary. He got involved in politics at an early age, first becoming a councillor at 21 after dropping out of university. He has since risen through the ranks to become one of Holyrood's most prominent figures.

He's seen as a steady hand and close ally of First Minister Nicola Sturgeon in the Holyrood group.

He'll be able to draw on the experience of former campaign managers Angus Robertson, the SNP leader at Westminster, who has his hands full defending his Moray seat, and John Swinney, who is under fire in his role as education secretary.

Peter Murrell, the party's chief executive and Nicola Sturgeon's husband, remains a force to be reckoned with at the top of the SNP. The Scotsman has described him as "a supreme political tactician who is one of the unsung heroes of the SNP's rise to power".

Unlike in Westminster, where advisers quit their day jobs to focus on party politics, the Scottish Parliament continues to sit and aides to the first minister such as Liz Lloyd and spokesman Stuart Nicolson will stay in their roles.

UKIP

This time around MEP and former Daily Express journalist Patrick O'Flynn is set to be an influential figure within UKIP's campaign. He ran former councillor Lisa Duffy's leadership bid, which focused heavily on an anti-multicultural message. He is close to the leader, Paul Nuttall, and is thought to have worked on the manifesto alongside party deputy chair Suzanne Evans.

Green Party of England and Wales

The Greens' campaign will be led by Nick Martin, chief executive of the party, who has previously stood as a candidate in Southwark and headed several legal practices before that. He has also overseen the manifesto-writing committee, which is made up of the party's co-leaders, and policy leads Sam Riches and Sam Pancheri. The Greens stress that policies are consulted on widely among members.

Plaid Cymru

Adam Price, AM and ex-MP for Carmarthen, is coordinating the general election campaign for Plaid Cymru, with an emphasis on speaking for Wales in the Brexit process. The party is counting on some unpredictable multiparty races in a number of Welsh seats. Gareth Clubb, a former director of Friends of the Earth Cymru, remains chief executive.

Northern Irish parties

There's an issue of strained resources for the Northern Irish parties represented at Westminster, as they have only just fought an assembly election and there could be another one this year, pending the outcome of talks on restoring devolved government. Timothy Johnston, long regarded as one of the most significant officials within the DUP, will be in charge for the largest Northern Irish party at Westminster.

But the electoral maths will be difficult for any strategist to calculate this time, with pacts between the DUP and UUP in two seats, Traditional Ulster Voice fielding only one candidate, and Sinn Fein enjoying improved fortunes since the renewable heating scandal.

Profiles by Esther Webber. Illustrations by Gerry Fletcher.