Following a dedicated effort from both girls, 18-year-old Mecia took the edge, her performance deemed 'fierce' by judge Lisa Snowdon.
Catwalk contest: 18-year-old Mecia Simone Simson was crowned Britain's Next Top Model after a walk off with Sophie Sumner, right, 18, at a PPQ fashion show
'I was sure would Sophie get it. The ten seconds waiting for my picture to appear seemed like days.
'I was mortified that I had to stand there and lose in front of the friends and family who'd come to watch the final catwalk show.'
And after months of living cooped up in a house away from friends and family surrounded by bitching and back-stabbing, Mecia says the proposal that came from her fiancé via video link gave her the lift she needed to win the show.
Winning shoot: Mecia's portrayal of Eva Peron wowed the judges, who said she'd managed to convey both emotion and power in her photograph
And in the final week of the competition, Mecia had experienced firsthand the duplicitous nature of Sophie, also 18, after her rival had branded her 'dull' and 'uninspiring' in an interview.
'I was really upset by her comments and confronted her straight away. I knew then that I had to look out for myself, and it made me even more determined to win.'
EnlargeThe fledgling model had earlier seen 20-year-old Jade McSorley placed third following an Eva Peron photoshoot in Buenos Aires, when judges commented the former anorexic was too thin and not yet strong enough to earn the title.
Genuine: Mecia harnessed the sadness she'd felt over the course of filming to produce the emotion that so impressed the judges in her shoot
But Jade herself was philosophical about her loss, saying today she felt it would have sent out the wrong message to other girls if someone with such a slight physique had won.
'I'm glad I didn't win.' she confessed. 'I didn't want girls to think being my size makes me the best model.
'All I need is more time to beef up and I'll be there. I know that if I want this I have to do something about it.
'Maybe I'm not Britain's Next Top Model, but I know I'm a good model.'
In what Lisa Snowdon said was the closest ever BNTM contest, runner-up Sophie was deemed much improved, impressing the judges with her progress - despite her reputation as the house bitch.
Panel judge, photographer Huggy Ragnarsson, who had previously said Sophie looked like 'an evil Geri Halliwell' and 'a stuck-up, stand-in Girls Aloud singer' commented that the blonde restaurant worker had transformed from a commercial model into an editorial - or high fashion - model over the course of the series.
Admitting it was devastating to lose, Sophie defended her behaviour on the show, claiming that in her constant bitching about the other girls in the private diary room - known as 'bish bash' sessions, she was simply giving the producers the spice they wanted to see.
Picture perfect: Runner-up Sophie's photo of a penniless Eva Peron moved the judges to tears. 'She gave me her soul,' said photographer Huggy Ragnarsson
'I figured out early on that it would help me to be the outspoken one and, of course, the producers loved it, constantly telling me how great I was in bish bash.'
'I genuinely think that when I was in the bottom two those first couple of weeks it was the character I'd been playing to the cameras that helped me scrape through'
And Sophie wasn't only savvy in her self-casting. She saw other girls' faults turned into storylines after their emotional outbursts, so she had the foresight to keep major insecurities about her stress-related acne flare-up to herself.
Enlarge'I locked myself in the bathroom and cried about it, but I was determined never to mention it in front of the cameras.
Beauty shot: 'Sophie opened her eyes, looked up to heaven and gave us her heart,' rhapsodised judge, milliner Louis Mariette, of this photograph
'Sure enough, it never became an issue, whereas Jade's anorexia was a constant focus, and Mecia's bad photoshoot in Argentina became the subject for an entire episode after she cried.'
EnlargeHer bad skin issue - which was mentioned just once, by photographer Terry O'Neill while shooting a beauty campaign - begun when Sophie was a teen and was something that had plagued her while at school.
Second best: Runner-up Sophie Sumner launches a shower gel in London today
'I came across as confident but I wasn't a strong person before the show. My skin really got me down. I actually couldn't have talked about it anyway - I'd have welled up.'
But despite their fondness for Sophie, after much deliberation, the judges chose down-to-earth Mecia as the winner, saying she was 'once sparkling wine, but is now Dom Perignon champagne.'
Her prize, a year's modelling contract with Models 1 and a cover shoot with Company magazine, will elevate her from wannabe model to the real thing overnight.
Sophie, on the other hand, will have to go it alone, facing the prospect of trawling London's modelling agencies to find one that might take her.
In the meantime though, runner-up Sophie has already made tracks in her new career, launching a Skin Bliss shower gel today in central London.
Sophie won the contract during a challenge early in the competition, and today donned a bikini to pose in a shower cubicle in London's Soho Square.
In a move that proved the producers were making the most of their new, larger budget, Model Jodie Kidd and Peaches Geldof - a regular at London fashion Week and a PPQ model/designer herself - made guest appearances on the final show, brought in to advise the girls on the best way to make an impact on the catwalk.
The girls were taken on two foreign trips - to Iceland's Blue Lagoon for a freezing cold photoshoot - and to Buenos Aires, where the final weeks of the competition were played out.