For all the candidates there was much to prove - whether it was shifting the focus away from gaffes, living up to expectation and hype, or simply doing everything they could to make a last ditch plea for votes.
The theme this time was the economy, but a range of topics were covered including immigration. But how did they get on when it came to getting their message across? Below, our team of experts have their say.
All the candidates are hoping this debate will give them a leg up in the polls
SPEECH AND LANGUAGE
NAME: Max Atkinson
EXPERTISE: Public speaking and speechwriting
"It was as if, at last, we got a proper debate," says Max Atkinson, of the final encounter between the three men.
"They really were arguing and showing some anger and passion. They've got the hang of it."
Atkinson says all three candidates have shown measured improvement in the way they've debated. By his assessment, Nick Clegg has "come on leaps and bounds" in the way he's been able to say things which resonate with people, and by using imagery.
The use of rhetorical questions is one of the most powerful techniques in the armoury of the debater, says Mr Atkinson. He notes it was by encouraging the audience to anticipate the answer to his questions that Nick Clegg was using this method to his advantage. Mr Clegg also deployed powerful imagery in his speech, using the idea of people being "in the shadows" during the immigration discussion.
Reasons to be cheerful, part three
Both David Cameron and Gordon Brown unleashed an alternative, but trusted, speech making technique to hammer their points home. "I lost count of the number of times they were using three part lists," says Atkinson of the two leaders, who rattled points off in triplets on a number of occasions.
Three part lists, he says, are a stock in trade when it comes to successful public speaking. It's a technique regularly employed by US President Barack Obama, who used the technique more than 25 times in his victory speech in Chicago in 2008.
Of Messrs Cameron and Brown - Atkinson says the Conservative leader showed he was "quite good at debates and was more assured than during the first one", while the Labour leader "risked losing the audience by being too technical and detailed".
Both chose to refer to the other at very different levels of formality. Gordon Brown called David Cameron, "David", while Mr Cameron consistently referred to Mr Brown as "The Prime Minister".
"Gordon Brown was doing the chummy thing, and David Cameron was doing something which was more distant, by referring to Gordon in the third person."
While much of the week has been focused on gaffes on the campaign trail, Atkinson says the overriding theme of all three debates has been a lack of on-stage gaffes.
"All three of them stayed on the tightrope".
STYLE AND FASHION
EXPERTISE: Celebrity stylist and personal coach
"In the first week they all looked like they were seeing the headmaster at school, as if their mummy's groomed them. Last week they went down a notch, but this time they all look re-groomed again".
For our image expert Ceril Campbell, sartorial style was at its best this week for all three candidates, but to differing degrees.
"Gordon Brown started off looking dishevelled. He has the proper suit and the proper tie but somehow his clothes seem to come all out of place," she says.
Campbell adds that part of the reason for this might be because Mr Brown moves much more when he speaks, whereas David Cameron remains largely still, so appears tidier.
The ties have it - Brown's 'daring' patterned tie, Cameron's party blue and Clegg's burnt orange
"Mr Cameron is, without question, the most sharply dressed," says Campbell, who notes the Conservative leader wears his tie in a much tighter knot than his Labour rival.
In style terms however, there can be advantages a less polished look, she argues.
"While David Cameron is a bit more dapper in his dress it can make him look less believable, whereas Gordon Brown looks more real, and Nick Clegg who looks more relaxed in the way he wears his clothes."
Given that the three men all chose similar styles of suit, the tie is the only item of clothing that injects colour and perhaps personality into the proceedings. This week David Cameron stuck to Tory blue, Nick Clegg to a Lib Dem-esque orange hue, while Gordon Brown opted for something a little different by wearing a spotty purple number.
But patterns can be a risky choice, says Campbell, because they risk diverting attention from what a person is saying.
"I don't like the grey suit," is our style expert's verdict on Nick Clegg's choice of attire. "The lighter your suit goes, the less authoritative you look on television."
All three looked "very shiny" this week, says Campbell, who assumes it was either very hot in the venue or that they weren't wearing enough make up. In the case of Mr Cameron she detected the merest hint of a five o'clock shadow on his upper lip - the merest echo of Richard Nixon's notoriously unshaved look from the 1960 US presidential debate? But it might just be he wasn't powdered down enough, she says,
NAME: Jason Vit
EXPERTISE: ESU debate coach
"This was the best of the three in pure debating terms because it became a debate of principle... a debate about big ideas and big concepts," says Jason Vit.
Vit describes the last of the three debates as "much more aggressive" and "highly combative", a sign perhaps of the fact it is the last chance the candidates get to make their pitch before the vote next week.
Our expert noted how all three used "tag words" - repeating a single word in a number of contexts.
Mr Cameron used the word "grip" several times to illustrate points, while his Lib Dem counterpart talked of things being "fair". Mr Brown's tag word, our expert says, was "women", having used the word on a number of occasions in the course of the three debates, when talking about policies.
Over the weeks, Vit says the "dynamic of the debate has evolved" - what began as a soft approach in the first one, has moved to one where all candidates "were really fighting and were willing to attack the other two candidates equally".
The stage was set for the third and final debate
Summarising the leaders' performances Vit says Gordon Brown was less personable than his opponents, but maintained a good command of knowledge, expertise and facts.
David Cameron, he believes, had finally relaxed into the environment after a wobbly first debate. His strength, argues Vit, is being able to maintain the focus on the issues he wants to talk about.
Lastly, Mr Clegg has maintained, in our expert's view, his ability to perform credibly as an orator, and to engage.
NAME: Harry Witchel
EXPERTISE: Body language and psychobiology
"The body language dramatically changed in the debates," observes Harry Witchel.
He notes more smiling and laughter, although not in a necessarily natural way.
"All the laughter that appeared were signs of weakness. You saw loads of smiles and almost all were examples of people ever so slightly losing their self control."
Of the three, says Mr Witchel, David Cameron grinned the least, maintaining a serious facial expression, which he gets by moving his eyebrows slightly together and down. This had the effect of making him appear very focused.
The Conservative leader also appeared more relaxed than in previous debates, says Witchel, who says his posture played a big part.
David Cameron leaned into his left shoulder to make him relax
"When he mentioned points he regularly switched between standing straight up and leaning his left elbow against the podium. That movement gave his shoulders a freedom that meant this time he looked much less stiff."
In this debate all the leaders criticised each other in equal measure. There was none of the 'I agree with Nick' language we heard in the first debate. The change in tone, argues Witchel has had the effect of changing the body language of Nick Clegg.
"By being on the defensive Clegg's look changed dramatically. In particular he laughed in exasperation more," he says.
Witchel also observes the Lib Dem leader appeared to be imploring the public to vote for him by raising the pitch of his voice, putting his hands together and raising them in front of him, in a gesture our expert describes as the "beggar pose", which is used to gain trust.
"Gordon Brown's body movements were much bigger and wilder," says Mr Witchel.
Mr Brown who has in the past been criticised for his stilted body language on YouTube videos and television appearances, admits presentation is not his biggest strength.
Of all three candidates, the Labour leader is the least controlled in his body movements, says Witchel. "He has in a sense let himself go," he says, noting the prime minister could be seen shaking his head more when others spoke, and nodding with conviction on each point he was making.
In all three debates Nick Clegg and David Cameron have rotated their position on the stage, while Gordon Brown, who is blind in his left eye has remained to the left of his opponents. Mr Clegg was on the right of the stage in the first week something which arguably benefited him in the first debate as it allowed him to present himself as the outsider, but our expert argues this position didn't necessarily work to his advantage this time.
"It wasn't clear who he had to look at or which way. In the first debate Brown and Cameron left Clegg alone so he was able to attack them as a group as he moved his arms out together".
NAME: Anila Baig
EXPERTISE: Features writer and former TV reviewer
"It was a bit like Harry Potter when they have their assemblies," says Anila Baig, of the setting for this week's debate.
The grand, high ceiled hall at the University of Birmingham had a Hogwarts-esque atmosphere - in keeping with this theme, Baig says host David Dimbleby was "a bit like a wizard presiding over things."
Did this atmosphere make for a magical televisual experience?
"It was definitely different - this was more colourful," she adds referring to the screen behind the three men which gradually changed shade during proceedings.
If last week was the sequel, then maybe a third helping was a bit too much she argues, pointing out that much of the ground which was covered was a repeat from previous debates.
The hall looked like something out of Harry Potter, says Anila Baig
Despite pleas from the BBC to change its time slot, the hugely popular Coronation St was head-to-head with the start of the debate. Baig resisted the temptation to channel hop, unlike previous weeks, but even though she stuck with it in its entirety, there were still things she believes could've added to the overall entertainment value, such as audience participation.
"When a questioner asked a question and he nodded - it was like oh my god he's nodding! "If there had been more natural audience reaction or maybe even a heckle that would've been good."
The rules of the debate banned the audience from clapping, something Baig would like to see changed if televised debates happen in another election campaign.
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