Last week, Cadbury and Kraft agreed terms for an £11.6bn takeover. It ended a long, drawn out and very public campaign by Cadbury to preserve its independence.

Cadbury's unions have led the opposition to the takeover, warning that thousands of jobs will be put at risk. Kraft now has a considerable amount of debt and a record of aggressive cost-cutting. The Unite union put together an opposition document for Cadbury's shareholders.

Kraft has stated that it expects "to ­honour Cadbury's commitments to sustainable and ethical sourcing, including Fairtrade" but it looks unlikely that Kraft would continue to expand its use of Fairtrade cocoa beans into brands beyond Dairy Milk.

The deal has re-shaped the global chocolate industry, which is now dominated by just four large companies: Kraft/Cadbury, Mars, Nestle and Ferrero. This excellent interactive graphic at the Guardian website shows at a glance the new companies and their product range.

Nestle is now in the unsual position of being third place, behind the Mars and the new Kraft/Cadbury giant, an unfamiliar role for the world's largest food corporation. It might not remain that way for too long as it is eyeing up Hershey, an American company with an iconic status similar to Cadbury in the UK.

As reported widely over the past few weeks, Fairtrade Dairy Milk chocolate bars are at long last rolling off the production line at Cadbury’s Bournville factory. This is a momentous, if long overdue, event for the fair trade movement, increasing all UK Fairtrade sales by 25% in one swoop and making the Fairtrade Mark visible in many more retail outlets.

The Fairtrade certification of Dairy Milk is a massive piece of ‘choice editing’, in a similar way to when Sainsbury switched all its bananas to Fairtrade. Usually ethical consumers have to make an active choice when buying Fairtrade products. When switching completely to Fairtrade bananas, Sainsbury addressed the fact that most people won’t actively seek out products that address issues such as sustainability and human exploitation, but will buy them when they are their only choice and they are right under their nose. The fact that Cadbury has followed suit by converting the most popular chocolate bar in Britain to Fairtrade, so placing Fairtrade in every newsagent and supermarket in Britain at no extra cost to the consumer, is a welcome development.

The development does also mark a big shift in the balance of power within the fair trade movement, raising all the big questions that arise when multinational companies adopt the Fairtrade Mark. So while it is an excellent thing, we need to be wary and thoughtful about the long term impact, and in particular ensure that the Fairtrade mission is not compromised or weakened in any way.

The last two months have seen two of the biggest chocolate industry players announce major ethical certification initiatives.

Cadbury's Dairy Milk bar will be Fairtrade certified in the UK and Ireland by the end of 2009, with plans to convert more of their range, and Mars are working with Rainforest Alliance to sustainably source all their cocoa by 2020, starting with Rainforest Alliance certification for the Galaxy bar in 2010.

To put these announcements in context and explore their significance, we put some questions to Mars and Cadbury, and to three external commentators...

Short film by Reuters with Divine Chocolate welcoming British confectioner Cadbury's decision to convert its biggest selling chocolate bar, Dairy Milk, to Fairtrade.

Cadbury and the Fairtrade Foundation have announced that Cadbury's Dairy Milk chocolate bar, and its hot chocolate beverage, will become Fairtrade certified in the UK and Ireland by the autumn of 2009.

Dairy Milk is the UK's best selling bar, with 300 million of them being produced every year. The chief executive of the company, Todd Stitzer, says he plans to convert their other chocolate brands to Fairtrade "as soon as we can do it". Dairy Milk represents 20% of Cadbury's chocolate range.