Preston, who joined the FAU in July 2003, has been outspoken about his disagreement at the government's proposed plans to ban pre-watershed junk food advertising to children.
He was part of a coalition of the food, soft drink and advertising industries last month to submit a proposal to the media regulator Ofcom to avoid a possible all-out ban on junk food advertising before 9pm.
Preston was sceptical about the effect of a ban. He said that "a ban on pre-watershed television advertising for certain foods would be a short-term, populist and disproportionate response, which is unlikely to have much impact on the problem of obesity".
Preston was named to the PR Week power 100 in 2004, cementing his place in the industry. He is described as having a logical, measured approach, which has earned him the respect of his peers who trust the former Cereal Partners managing director to put his extensive experience of the food industry to good use.
In addition, Preston has hosted many parliamentary debates on behalf of the FAU on the issues of food and drink advertising.
Responsibility for the FAU will now be passed to Andrew Brown, the director-general of the Advertising Association, and Sue Eustace, its head of public affairs.
Preston said: "My goal has always been to ensure that the FAU argues on the basis of sound evidence and emotion. Only this can bring about effective future policies."
Brown added: "Jeremy has given outstanding service to the business at a very busy and demanding time for which we are very grateful. He recognised that, now the Ofcom consultation has closed, it was an appropriate time to fulfil his wish to stand down."
Prior to joining the FAU in 2003, Preston spent 13 years as managing director of Cereal Partners UK, the breakfast cereal joint venture between Nestle and General Mills.
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