In her role as marketing chief of the Department of Health (DoH), Mitchell is behind the new Change4life strategy, for which ads broke this month, featuring figures created by Aardman Animations. They have been hard to miss. The £8.7m campaign, created by M&C Saatchi and running across TV, outdoor and print, objectively communicates the story of the UK obesity problem and forms part of a wider £75m, three-year marketing campaign.
Even those who rail against the nanny state and government interference in social problems are willing to concede that doing nothing is no longer an option in this area. The facts speak for themselves. According to the influential 2007 Foresight report on tackling obesity, without intervention, 90% of today's children will be overweight or obese and at risk of serious diseases by 2050. If left unchecked over the same period, this group is forecast to cost the nation £50bn - equating to an alarming 50% of the NHS' budget per year.
Around this time last year, the government announced its intention to launch the unprecedented drive. This led to a host of press stories predicting that the campaign would feature shocking images to scare the public out of its slothful ways. As we now know, these reports were well wide of the mark.
Mitchell says the department has spent the past 18 months talking to parents, during which time the need became clear to ground the problem in the everyday, and distance it from tabloid tales of 14-stone nine-year-olds.
'We recognise that it is mums that we need to influence to say obesity is not about freak-show issues,' adds Mitchell. Despite rising child-hood obesity figures, only 4% of parents believe their child is overweight or obese, while a scant 6% know of the condition's link to cancer.
Mitchell struck on the simple campaign message that fat in the body can lead to serious diseases, and has made sure to avoid any focus on aesthetic issues. She is pleased with the early results. In the first four days of the campaign, the website received more than 100,000 hits.
The work was also peer-reviewed by a group of marketing academics, and Mitchell says that while they did have a few criticisms, overall feedback was positive.
Next month, the TV creative will be used to promote the direct marketing aspect of Change4Life, which is being handled by EHS Brann. A questionnaire aimed at discovering families' eating and exercise habits will be sent to 11m households.
Mitchell hopes Change4Life will follow in the DoH's strong tradition of effective public health campaigns, such as that flagging up the dangers of AIDS, which ran in the 80s, and 30 years of anti-smoking work, credited with making the 2007 smoking ban palatable to the public.
Such is the scale of reining in obesity that the DoH has taken inspiration from social movements such as Make Poverty History and Comic Relief. As a result, there is much more to the drive than the ad campaign alone. A broad coalition of charities, grass-roots community groups, supermarkets and food companies has come on board.
The resultant group operates under the name Business4Life and is co-ordinated by the Advertising Association.
The involvement of the corporate set, including companies such as PepsiCo, Kellogg and Tesco, has, predictably, sparked controversy. Lobby groups claim that their presence risks undermining the programme, as these companies peddle 'junk' food and will exploit the Change4Life branding for their own ends.
However, Mitchell is adamant that the Business4Life coalition, which has pledged to make a sizeable contribution of £200m, has a vital part to play. 'It is crucial that we work with the commercial sector,' she says. 'They own the brands that people eat and the places where people shop.' Moreover, she adds, the terms of engagement governing the use of the Change4Life branding has been 'thrashed out' by the charity partners and there is no question of brands just 'sticking the logo on-pack'.
The irony of collaborating with companies that have been among the loudest and most fierce critics of the DoH's proposed traffic-light nutritional-labelling scheme is not lost on Mitchell. 'Yes, there is that, isn't there?' she adds with a chuckle. However, she maintains that it is possible to work with brands for Change4Life while her department's policy team continues the labelling debate.
Grappling with issues such as these seems a million miles away from working at BT, where Mitchell spent the majority of her career in the 80s and 90s. During her time at the telecoms company, she oversaw a raft of iconic advertising, such as the 'Beattie' ads featuring Maureen Lipman, which were aimed at highlighting different occasions to use the phone, followed by the Bob Hoskins 'It's good to talk' drive.
After branching out on her own into consultancy, Mitchell landed her first Whitehall position at the government's Office of the e-Envoy. There she created a brand positioning for Directgov, the portal for the government's online activity.
'People said that I would never get used to it, coming from the hard-nosed commercial sector to the public sector, but there were more parallels than differences,' she says.
Before arriving at the DoH, Mitchell launched the government's internal 'Engage' programme, which involved rooting out good examples of strategic market-ing and communication from the private sector and adapting it to the requirements of the public sector. As part of this activity, she probed companies including BT, Procter & Gamble, Disney and Unilever.
'The public sector wasn't broken but needed to look outside for best practice,' she says. 'The big thing we took out was to make sure that customer insight feeds into all our processes. We have been too reliant historically on advertising agencies doing all our insight.'
Although Mitchell is keen to highlight the similarities between the private and public sector marketing worlds, she has no regrets about her switch. 'It's about real people and real lives,' she adds.
Mitchell describes her current role as being about 'trying to stop people doing things that they find intensely pleasurable'. With this in mind, progress on a campaign such as Change4Life has to be measured not just over years, but decades. It appears, however, that Mitchell has got off to a strong start in tackling a difficult task.