Jamie Oliver’s name has become synonymous with hearty, homemade dinners, down-to-earth kitchen chat and happy family scenes. And so he’s been an ideal figurehead for campaigns for healthier kids and a healthier planet. In the last decade we’ve seen him improving school meals, working with government to tackle obesity, and speaking out against climate change. We have come to know him as both a great chef and an ambassador of brighter, healthier futures. And he’s built a huge and admiring following as a result.

That’s why the announcement that he’s going into business with the oil giant Shell was so disappointing. The contradiction that he’ll be revamping the oil giant’s food offering is unmistakable to those concerned about climate change – he has been praised as an “environment champion” by the UN’s environment programme after years of campaigning, while Shell’s business plans don’t come close to doing what is required to address the climate crisis. But it’s even more depressing if you know about the allegations made against Shell, in a bribery case involving one of Africa’s most valuable oil blocks. Oliver’s £5m deal pales in comparison to the sums coming up in the courtroom: the prosecutor is alleging billion-dollar bribes.

But we’ll forget about the allegations of corruption for a moment – Shell deny the claims, saying: “Based on [...] all of the information and facts available to us, we do not believe that there is a case to answer in this matter”. But far from “Making the Future”, as Shell’s PR team would have us believe, Shell could be set to take the future from Nigeria. In 2015, more than half of children under five in the country were “stunted or wasted”. Since then Nigeria has become the country with the highest rate of extreme poverty in the world. The £6bn Nigeria is alleged to be set to lose from the secret terms in this deal could train six million teachers, or fund the federal health and education budgets twice over. Maybe Jamie’s team could help Shell work out how many healthy school dinners they could make for that kind of money. It’s clear that Nigeria could really benefit from them.

But I doubt that’s why Shell picked Jamie. As an ambassador for better futures for children and the planet, I imagine they targeted him as a face to improve their reputation. It’s one of many bright ideas they’ve had to try to remedy their sullied profile and keep a steady flow of young, bright and enthusiastic graduates joining their team. Their live events and their digital campaign are unashamedly aimed at children and teenagers, with the likes of Pixie Lott and Jennifer Hudson literally dancing to Shell’s tune.

Trying to bring on board a family man who cares about the future of children and the planet is certainly a shrewd move for a company whose operations are jeopardising those very things. But, like Jamie, I’d like to see a healthier planet, well-fed children, and an end to corruption. So for Christmas, I’m asking Jamie to think again about using his great campaigning skills and huge popularity to bolster Shell’s public profile, whilst damaging his own.

• Ava Lee is Global Witness’ senior anti-corruption campaigner