Jose Manuel Barroso has said the concerns of UK citizens towards the European Union merit a “substantive response”.

In a speech at Chatham House, the Portuguese politician who was at the helm of the European Union for ten years sought to address concerns about EU interference and the budget and rule out ‘march towards a superstate’.

But he once again reiterated the battle that David Cameron would have at providing real changes to the immigration rules between Member States.

“I believe that any further changes to address some of the concerns raised [about immigration] should not put into question this basic right, which cannot be decoupled from other single market freedoms.” he said in a direct reference to the ‘fundamental freedoms’ of the European Union.

“The Commission has always been ready to engage constructively in this discussion. But changes to these rules need all countries to agree.”

David Cameron’s proposed changes to immigration from within the EU have continued to hit stumbling blocks as senior figures point out that anything which required a change in the Treaties would require unanimity of all 28 countries.

“Our union is strong because it respects diversity; our Treaties guarantee that, for those who accept the fundamental rules of the club there is always a place, and there is always equality of treatment.”

And Mr Barroso shared his vision of the future direction of the EU in a direct appeal to British voters who have become increasingly sceptical about the UK’s place in the political union.

“My vision of the Europe is as a union of citizens who share the same basic values of peace, freedom, democracy, and a just society” he said.

“A union which is stronger because we cherish our diverse histories, cultures and traditions” adding that he “may prefer a glass or two of good red wine than a pint of beer when I am out on the election trail” – a direct nod to beer drinking UKIP leader Nigel Farage whom he sat next to in the European Parliament for five years.

And he reiterated the ways in which the UK has kept separate control over key areas of policy including keeping the pound and opting out of the Schengen Agreement on free movement of people.

“I have never challenged the UK’s preferences on the euro – and indeed have personally ensured that every proposal we have made to reform financial services legislation has guaranteed the integrity of our internal market and fairness for everyone, whether in or out of the euro.”

“I have never argued you should join Schengen and open your borders, nor did I criticise your decision to exercise your opt-out rights under the Treaties. But I have worked to ensure that the UK can re-join the 35 police and criminal law measures identified by the government as key for bringing security to the British people. And that is even more important given the very real and direct threats our societies face today.”

And there was even a nod towards the curvature of cucumber directive which was one of the laws much derided by tabloid newspapers – although no mention was made of bendy bananas.

And he issued a direct call to pro-EU politicians in the UK to put the positive message of EU membership to the voters, telling them to look at the strategy of the ‘YES’ campaign in the Scottish referendum.

“Even though I understand that emotionally the case for keeping the United Kingdom are different in nature, rationally many of the arguments used by the three main political parties in the Scottish debate are just as relevant for British membership of the EU.”

“And you need to start making that positive case well in advance, because if people read only negative and often false portrayals in their newspapers from Monday to Saturday, you cannot expect them to nail the European flag on their front door on Sunday just because the political establishment tells them it is the right thing to do.”

Meanwhile Downing Street has rejected claims by Mr Barroso that the UK would be making a “historic mistake” if it left the EU, reports the BBC.

Mr Barroso said the UK would have “zero influence” if it left political union, despite being a global trading nation and part of the Commonwealth of 53 nations.

But a spokesman responded saying the status quo was “unacceptable” and changes were needed.

The Prime Minister has pledged changes on immigration from within the EU in a response to polls showing support increasing for UKIP.

It is not known whether any policy announcements will be made before the Rochester and Strood by election on the 20th November, where currently defector Mark Reckless is leading in the polls on 40 per cent, according to Survation.