Mr. Kings comments come shortly before the Supreme Court rules in January 2017 as to whether the UK parliament should also be involved in the details concerning triggering Article 50 of the Treaty of Lisbon, which formally begins the process of Britain and Brussels negotiating Britain's withdrawal from the EU and its new post-EU relationship with the remaining 27 countries.
Mr. King questioned whether the UK should remain in the single market and the customs union.
"I don't think it makes sense for us to pretend we should remain in the single market and I think there are real question marks about whether it makes sense to remain in the customs union," Mr. King said in an interview with BBC's Radio 4.
The former Bank of England governor said that Britain's exit from the European Union could undermine the UK government's ability to sign trade deals with countries outside of the European bloc.
UK Prime Minister Theresa May and Trade Secretary Liam Fox recently said they wanted to agree on new trade agreements with non-EU countries as soon as possible after Brexit and have already started informal talks with some of them.
Mr. King has said that he believes Britain would be better off economically out of the EU single market.
"Being out of what is a pretty unsuccessful European Union — particularly in the economic sense — gives us opportunities as well as obviously great political difficulties."
Mr. King believes Brexit holds a number of opportunities for the British people, one of which would be a complete re-work of the agriculture system and to revise the relationship with the Republic of Ireland.
Lord King is totally wrong about "developing opportunities with the Rep of Ireland". The Irish view of #Brexit is overwhelmingly negative.— Aidan O'Rourke UK/EU (@AidanPolyglot) December 26, 2016
"I think the challenges we face mean it's not a bed of roses, no one should pretend that, but equally it is not the end of the world, and there are some real opportunities that arise from the fact of Brexit we might take," Mr. King added.
These statements from the former BoE governor come at the same time as research from the Change Britain campaign group, a UK organization designed to make Britain's departure from the EU a successful one. Change Britain states that US$29 billion a year is on offer, if the UK Government pursues a 'clean Brexit' and decides to leave the EU's single market and customs union.
The research shows that the UK would be over US$549 million a week better off through a mixture of taking back control of the money given to the EU each year, lower regulatory burdens on British businesses and through striking trade deals with growing parts of the world's economy.