Mr Cameron set out the four key ways he wants to change the UK's membership of the EU in a letter to European Council president Donald Tusk, external in November:

• Integration: Allowing Britain to opt out from the EU's founding ambition to forge an "ever closer union" of the peoples of Europe so it will not be drawn into further political integration
• Benefits: Restricting access to in-work and out-of-work benefits to EU migrants. Specifically, ministers want to stop those coming to the UK from claiming certain benefits and housing until they have been resident for four years. But the European Commission, which runs the EU, has said such a move would be "highly problematic". Ministers have reportedly been warned by the UK's top civil servant this could be discriminatory and any limits may be reduced to less than a year

Image source, EPA

• Sovereignty: Giving greater powers to national parliaments to block EU legislation. The UK supports a "red card" system allowing member states to scrap, as well as veto, unwanted directives. But this may only be triggered by states acting together, not the UK acting alone
• Eurozone v the rest: Securing an explicit recognition that the euro is not the only currency of the European Union, to ensure countries outside the eurozone are not materially disadvantaged. The UK wants safeguards that steps to further financial union cannot be imposed on non-eurozone members and the UK will not have to contribute to eurozone bailouts

Committee convener Christina McKelvie asks how Norway's relationship with the EU has affected its oil industry and energy policy.

Niels Engelschiøn from the Ministry of Foreign Affairs, Oslo says it is difficult to see how it would have worked within the EU.

Image source, bbc

Mr Engelschiøn says there are difficulties due to different interests.

He says Europe is Norway's main market and the European Economic Area has helped in oil and gas sales. 

Dáithí O'Ceallaigh from the Institute of International and European Affairs and former Irish Ambassador to the UK says being a member of the EU has actually led to more independence.

Mr O'Ceallaigh says: "Before Ireland joined it could sing to the birds,sing to the wind but it did not have any affect."  

Dáithí O'Ceallaigh from the Institute of International and European Affairs and former Irish Ambassador to the UK says 20% of the greater Dublin area are immigrants, mostly from the rest of the EU.

Ireland does not have as many refugees coming in as other European countries, he says.

Image source, bbc

The country has not signed the Schengen Treaty.

Mr O'Ceallaigh says there is very little anti-immigrant feeling as they are all working and all contributing to the economy.   

The European Union is an economic and political partnership involving 28 European countries, external. 

It began after World War Two to foster economic co-operation, with the idea that countries which trade together are more likely to avoid going to war with each other..

Image source, bbc

It has since grown to become a "single market" allowing goods and people to move around, basically as if the member states were one country. 

It has its own currency, the euro, which is used by 19 of the member countries, its own parliament and it now sets rules in a wide range of areas - including on the environment, external, transport, external, consumer rights, external and even things like mobile phone charges, external

Niels Engelschiøn from the Ministry of Foreign Affairs, Oslo says Norway has benefited from the free movement of persons.

Mr Engelschiøn says migration through Schengen and the refugee crisis are separate issues.

He says there have been 26,000 refugees coming to Norway.

Norway has closed the border to Sweden on a non-permanent basis, providing more control.

Professor Dr Andreas Auer LL.M from the Universities of Zurich and Geneva says it's impossible to give an annual figure as to what Switzerland contribute to EU programmes.

Image source, Reuters

But it can be said that the people and the country have benefited from these programmes, he says.   

Knut Hermansen from the Norwegian Mission to the EU, Brussels says the European Economic Area option is available to the UK if it leaves the EU. 

It would have to become a member of the European Free Trade Association first, he says.

Mr Hermansen says membership of the EEA would require negotiations with all current members.

The UK would have to accept the four freedoms of the EEA including the freedom of movement, he says.

These would be difficult negotiations.

The EEA provides for the free movement of persons, goods, services and capital within the internal market of the European Union (EU) between its 28 member states, as well as three of the four member states of the European Free Trade Association (EFTA): Iceland, Liechtenstein and Norway.

Agreement between the UK and the rest of the EU over David Cameron's reform proposals is possible next month, one of the leading negotiators has said.

Donald Tusk, president of the European Council, said he would table "concrete proposals" for discussion at February's summit of EU leaders in Brussels.

Image source, AFP

Should a deal be reached, it would open the possibility of a referendum on the UK's membership being held in June.

A poll must be held by the end of 2017, but the PM is thought to favour 2016.

Dáithí O'Ceallaigh from the Institute of International and European Affairs and former Irish Ambassador to the UK says there is a dissatisfaction with Brussels. 

People don't understand how Brussels works, he says. 

The former Irish Ambassador to the UK says there is an anti-politician feeling out there.  

He says David Cameron's negotiations on welfare with the EU are very difficult.

Professor Dr Andreas Auer LL.M. from the Universities of Zurich and Geneva says he would never consider the Swiss position of being a solution for anyone, as Switzerland is in a difficult position.

Prof Auer says one of the reason said no to the EEA was that it was felt powers that belonged to the Swiss Parliament and people would be lost. 

Image source, Reuters

The Swiss professor says the people have never been asked about EU membership as the politicians are scared to do so.

Most people are happy with the current situation, he says. 

Niels Engelschiøn from the Ministry of Foreign Affairs, Oslo says two parties are very against membership of the EU, the Labour party is split and the Progress party is split as well.

There are two parties in the centre who believe the EEA agreement is a good compromise.

The Agreement on the European Economic Area (EEA) is the mainstay of Norway's cooperation with the EU, and it ensures that Norway takes part in the EU internal market. 

The Schengen Agreement abolished the EU's internal borders, enabling passport-free movement across most of the bloc.

But the 13 November attacks by Islamic State (IS) jihadists in Paris, which killed 130 people, prompted an urgent rethink.

There was alarm that killers had so easily slipped into Paris from Belgium, and that some had entered the EU with crowds of migrants via Greece.

And in 2015 the influx of more than a million migrants - many of them Syrian refugees - greatly increased the pressure on Schengen.

One after another, EU states reimposed temporary border controls.

Dáithí O'Ceallaigh from the Institute of International and European Affairs and former Irish Ambassador to the UK says he has looked at Brexit.

Mr O'Ceallaigh says it is in the interests of Ireland to remain in the EU.  

Dáithí O'Ceallaigh from the Institute of International and European Affairs and former Irish Ambassador to the UK says his institute has produced a book entitled Britain and Europe: The End Game.

Mr O'Ceallaigh says it is necessary for the UK to be regulated either within or outwith the EU once and for all.

He says if the UK remained in the EU it could participate in the single market.

It could also remain out of the Euro, but all of the other member states, except Denmark, have a treaty to join the Euro, he says.

The former Irish Ambassador to the UK says the issue or the relationship between Euro members and those not in the Euro can be addressed.

Mr O'Ceallaigh says there could also be a security issue to deal with energy security and immigration from outwith the EU.   

Professor Dr Andreas Auer LL.M. from the Universities of Zurich and Geneva says there 135 treaties or agreements with the EU and members.

A guillotine clause binds all the agreements together, he says.

The professor says Switzerland also is more integrated than the UK, as it is a member of the Schengen agreement and the Dublin agreement. 

Professor Dr Andreas Auer LL.M. from the Universities of Zurich and Geneva says 55% of Swiss exports go to EU countries.

Switzerland is very strongly integrated with the EU, he says.

The Swiss professor says in 1992 came the first shock when the EEA agreement was not integrated. 

Prof Auer says the Swiss people said no to this, which led to a complex process of bilateral agreements with the EU and member states. 

It is one of the most complicated legal treaties you can imagine, he says. 

Niels Engelschiøn says Norway is fully integrated to the internal European market and the relationship with the EU is very close.

He says there is not an option not to cooperate fully with the EU, but membership is not on the political agenda.  

Niels Engelschiøn from the Ministry of Foreign Affairs, Oslo begins by saying Norway has said no to EU membership twice.

Mr Engelschiøn says in 1994 it was due to agriculture, fisheries and the sovereign principles.

He says the EEA agreement effectively ensures equal treatment from the EU and allows some input into the process.

Mr Engelschiøn says there are 74 other bilateral agreements with the EU, including Schengen and the Dublin Agreement.

This means Norway is more integrated with the EU than the UK.

European and External Relations Committee convener gets us underway by introducing the witnesses.