Lynton Crosby

Australian political strategist who has helped guide the careers of former Aussie Prime Minister John Howard and the flamboyant Conservative mayor of London Boris Johnson. Mr Johnson has praised him for "political sourcery" but opponents accuse him of being a master of the spin doctor's "dark arts". In his current role as election chief he has helped to stabilise discipline and boost morale among rank and file Tory MPs. His private business as a lobbyist and controversial connections to tobacco firms led to accusations he was keen the Tories dumped plans for plain packaging.

George Osborne

The Chancellor has bounced back after 2012's 'omnishambles' Budget and was recently named by David Cameron as a potential future Tory leader, leading some to speculate he could even be Prime Minister someday. Has a crucial role in an election campaign dominated by arguments about the economy.

He is also at the forefront of the "northern powerhouse" idea which Tories good will help them take seats outside of the South of England.

He has also had an image makeover recently, losing weight and with a more modern new haircut.

Paddy Ashdown

A former Royal Marine and International High Representative for Bosnia and Herzogovina, as well as, of course, the ex-leader of the Liberal Democrats.

A close confidante of Nick Clegg, Ashdown played a key behind the scenes role in the negotiations that led his party to agree to coalition government with the Tories in 2010. Now fighting hard to save the Lib Dems from losing huge numbers of its MPs.

He has already shown his combative style , including a spat with Alex Salmond, that Lib Dems hope can inspire candidates and canvassers in what will be tough weeks ahead.

David Laws

Lasted just 17 days in his first stint as a minister, in the job of chief secretary to the Treasury, before being forced to resign over his expenses in 2010. But he later returned as years later as an education minister and a minister in the cabinet office. A former banker he is seen as on the right of the party and was one of the original 'Orange bookers'

First elected to the House of Commons in 2001 as MP for Yeovil, as the then Lib Dem MP, one Paddy Ashdown, stood down.

In opposition he was once offered a job in George Osborne's shadow paw cabinet. "I am not a Tory," he famously told the new Chancellor. Seen by many Lib Dems as a safe pair of hands.

Douglas Alexander

Led David Miliband's campaign to be Labour leader and is now Ed's election chief. He was also heavily involved in last year's independence referendum campaign. The MP for Paisley is acutely aware of the challenge the party faces from the SNP in Scotland - some polls have suggested that he is on course to lose his seat. He also serves as Labour's shadow foreign secretary and played a crucial role in his party's decision not to sign up to international action in Syria in 2012.

Lucy Powell

Only elected to Westminster three years ago in the 2012 Manchester Central by-election, she had already worked for Ed Miliband in his bid for the leadership and served in his leaders office. In an earlier life worked for the pro-EU pressure group Britian in Euopre, whose alumni include Lib Dem minister and Highland MP Danny Alexander. Initially put in charge of childcare policy for Labour before her promotion to get current role she is often praised for being able to pull off that difficult task of being table to "talk human" her rapid rise has not always gone down well with all of her political colleagues.

Nicola Sturgeon

The SNP leader is setting the tone for the campaign, including through a number of speeches she herself has given in England, designed to reassure voters south of the border that they have nothing to fear from the SNP. Has made clear that she will lead any coalition negotiations with Labour in the event of a hung parliament in May.

Angus Robertson

The SNP's Westminster leader also serves as his party's defence and foreign affairs spokesman. Born in London, his mother is German and his is as a consequence bilingual. His early career included as a journalist in Vienna. First elected to Westminster in 2001, he served a campaign director for last year's independence referendum and co-ordinates the party's highly successful 2007 and 2011 Holyrood elections. He took over as Westminster leader from former First Minister Alex Salmond, who is now tipped to rejoin him as a colleague in the Commons in May's election.