PRESENTED and written by historian, Professor Martin Johnes, Wales: England's Colony? challenges some of the most fundamental ideas about Wales' historical relationship with England and its place in the world.

The two-part series, broadcast earlier this month on BBC Two Wales and available now on the BBC iplayer, was designed to stimulate debate about the past story of Wales, and challenge its audience to think afresh about some of the future constitutional choices facing Wales as it leaves the European Union.

Focussing on how Wales' relationship with England has shaped both the nation's development and how Wales sees itself, the programmes tell the story of an uneasy and unequal relationship between two nations living side-by-side. It examines Wales' story from its creation to the present day, examining key moments such as medieval conquest, industrial exploitation, the Blue Books, the 1919 race riots and the flooding of Cwm Tryweryn.

Martin argues that the conquest and oppression of the medieval period meant Wales was England's first colony, but that gradually over time the Welsh reconciled themselves to this position and became partners in and beneficiaries of the British Empire. The union of England and Wales was never an equal one, but in a democracy Wales has the freedom to choose whether it wishes to remain in the United Kingdom or not.

"Brexit is raising big questions about the whole future of the UK and its relationship with the world, which impacts upon Wales as well," says Martin. "There is a fair chance that if we see a hardline Brexit the UK could easily break up: it's not hard to imagine Scotland voting for independence and not impossible to imagine Irish reunification. It might not be on the immediate horizon, but I think they are both political possibilities in the way that has never been the case before and if that does happen, it raises questions for us in Wales about what we want to do and so I think it's important that we make decisions on our future based upon a proper understanding of what has happened in the past."

Throughout the programme, Martin argues that from the very beginnings of Wales, its people have defined themselves against their larger neighbour. That relationship has defined both what it has meant to be Welsh and Wales as a nation. Yet the relationship has not always been a happy one and never one between equals. The historian believes Wales was England's first colony and its conquest was by military force. It was later formally annexed, ending its separate legal status. Yet most of the Welsh reconciled themselves to their position and embraced the economic and individual opportunities being part of Britain and its Empire offered

"Our history is complicated, so if we need to make a decision on our future then we must base that on what must be right for Wales going forward, rather than based on anything that's happened in the past, he says. "Only in the later half of the 20th century, in response to the decline of the Welsh language and traditional industry, did Welsh nationalism grow.

"The problem with Brexit is we don't know what form it will take, which is obviously mad considering we were supposed to be leaving on March 29. It is so difficult to look forward but I think whatever happens, leaving the EU will be damaging to every sector of both the Welsh and British economies."

One thing that becomes clear throughout the programme is how power has shifted from the north of Wales to the south and Martin agrees this is still a major issue for the country's population when considering their future.

"I think north east Wales is often forgotten by people in the rest of Wales, despite it historically being such an important part of the country economically and culturally," he says. "The whole danger of the devolution project is there is no point replacing the dominance of the south east of England with the dominance of the south east of Wales. The point of the devolution project is to bring decision making closer to the people and one of its failures has been the fact people in the north east feel marginalised.

"Wales has never really had one single economy - the north has always looked east towards Liverpool and Manchester and the south has always looked east to Bristol. Historically the links between the north and the south in everyday life have always been relatively marginally. In the 19th century why would you sell things to the south when you have a huge market on your doorstep over the border?

"One of the lessons of Welsh history is that the border is porous and people have moved back and forth across it for centuries. There may be mountains down the middle of Wales but the border in some places is pretty invisible and whatever happens in the future that border has to stay open for economic and cultural reasons."

Martin made a number of visits to both Flintshire and Wrexham during the making of the programme, where he focused on events including the Mold Riots of 1869 and the building of the Pontcysyllte Aqueduct.

"The Mold Riots were unusual because what sparked them were real tensions between English and Welsh and they escalated into serious trouble," he says. "You had an English mine owner treating his Welsh workers badly and it showed that during that period the differences between the two were more than symbolic and had an impact in real life. In the north east of Wales you had two linguistic cultures close to each other and I suspect there was a lot of everyday tension.

"The aqueduct is so beautiful and it shows how the north east of Wales is not the industrialised, urban area that so many people imagine. Parts of it are beautiful with a great heritage.

"From a footballing point of view, north east Wales is also the birthplace of a major part of Welsh culture and it was well overdue for the national side to play a friendly in Wrexham recently."

With a book also accompanying the series which Martin says has had "great viewing figures", the historian is looking forward to more debate about Wales' future relationship with England and Europe.

"Our relationship with England is so complicated," he adds. "There has been tension, there has been oppression, but there has also been co-operation and conciliation as well."

Wales: England's Colony? is available to watch on the BBCiplayer.