The European Union and the UK resumed Brexit talks on Monday, but with less than two months left for the two powers to agree a trade deal before the December 31 deadline, they are still said to be some distance away from an agreement.

There remain several major sticking points, including EU access to UK fishing waters from 2021 and regulations on workers' rights, environmental protection and state aid designed to maintain a "level playing field."

UK Prime Minister Boris Johnson has repeatedly stated that the successful agreement of a trade deal is now up to the EU and that he's willing to walk away without one, but the bloc maintains that compromises must be made on both sides.

Pascal Lamy, the former director-general of the World Trade Organization (WTO) and a former EU trade commissioner, says the political terms of the divorce are clear but have been complicated by the UK's desire to maintain the economic benefits of being part of the EU.

He said: "These Brexit negotiations are not about whether the UK should stay or not in the EU, they have decided to leave politically and the question is, how much do they leave economically and this translates into how free trade between the EU and UK has to be in the future."

Lamy also believes the EU is right to resist giving in to UK demands for a generous trade deal and says countries that choose to leave the bloc will inevitably pay an economic price for their exit.

"We remove borders in the EU when we harmonize our regulations," he continued. "If you want to disharmonize – i.e. separate the economic and social system of the UK from the EU, this will have consequences on trade. 

"Leaving the EU is about deleveling the playing field, how much they want to do that is unclear. One has to understand the EU will have a thin or a thick border depending on whether the UK exits a lot or a little [from] the EU regulatory and standard system."