LONDON (Reuters) - A British exit from the European Union would be a historic blunder that would dilute the country's clout in the same way as the Suez crisis did, the most pro-European Conservative minister in Britain's government says.
Prime Minister David Cameron has promised to try to claw back powers from the EU and put any new settlement to voters in an in-out referendum by the end of 2017, heightening fears that Britain could leave the club it joined in 1973.
Ken Clarke, a leading Europhile who attends weekly cabinet meetings, said an exit would make Britain a spectator of 21st Century history, scupper its alliance with the United States and banish it from the top table of European affairs.
"It would be an historic mistake of enormous proportions," Clarke, a "Minister without Portfolio" who has held most of the top posts in government going back 30 years, said in an interview as part of the Reuters euro zone summit.
"Our political influence in the world would of course be immediately diminished: the EU is the platform which enables us to punch above our weight," said Clarke, who served as Britain's finance minister from 1993 to 1997.
"We would remain in the single market, but we would just lose our voice, our vote, our veto, if you want to exercise a veto, on all the regulating of the market. We'd be reduced to the spectator role of the Norwegians, the Swiss, and Iceland and Liechtenstein."
One of Britain's most influential Europhiles, Clarke said it was folly to forecast the result of any future referendum on membership and that many British people were puzzled by Europe.
But he said ditching membership of the world's biggest economic area for the illusion of 19th Century sovereignty would be an event comparable to the 1956 Suez crisis, when British forces were forced by the United States to withdraw troops from Egypt, or the 2003 invasion of Iraq.
"Suez and Iraq were the two big disasters of the post-War world of my lifetime, so yes this would be the big political and economic disaster and in terms of our role on the world," Clarke said. "Suez in the end had a very beneficial role as it woke the British up and made them realize that the world had changed."
A British exit from the EU would also push the United States, which bluntly warned Cameron this year to stay within the EU, towards an alliance with Germany as the leaders of Europe, he said.
"If we left the European Union, the Americans would obviously look to the Germans as the natural leaders of Europe. Already, the German relationship matters to them almost as much as the British one and it would matter more if we were to leave."
Clarke cautioned that Britain's print media had fostered anti-European sentiment while the anti-EU UK Independence Party (UKIP) was winning the protest vote from people angry about immigration and the economic crisis.
"My views are never reported," Clarke said, adding that UKIP was comparable to Italian radical Beppe Grillo and the Tea Party movement in the United States.
"Because of economic distress it is not surprising that you get a large rather angry protest vote and that's what UKIP mobilizes," he said.
He said the proportion of pro-European Conservative lawmakers had diminished, but that only a minority of about 30 or 40 out of 303 Conservative members of parliament actually wanted to leave the European Union.
Clarke, who lists his proudest political achievement as paving the way for economic growth as Chancellor of the Exchequer following the pound's 1992 exit from the European Exchange Rate Mechanism, said Britain needed to reduce its debt.
"I was surprised we got such a firm reputation as a safe haven currency as we have such an appalling problem with deficit and debt and we do need a great deal of supply side reform," Clarke said.
"We devalued by 25 percent in the last five years and we still have a current account deficit so we have got to get a modern competitive economy and meanwhile we are burdened with quite an unsustainable level of deficit and debt."
The 72-year-old was somber about the chances of Britain ever joining the euro: "Not in my lifetime".
(For other news from Reuters Euro Zone Summit, click here)
Editing by Mike Peacock