The Tory peer called the EU the “slowest-growing economic bloc in the world”, adding: “There is no reason to believe this is going to change.”
He also said the UK could negotiate a trade deal outside the EU – because of the high demand for goods and services from British consumers.
Tariff-free access to the single market was “desirable but it is by no means essential”, he said.
Branding the 28-member bloc “unreformable”, he dismissed the warning from leading businesses against quitting the EU.
He recalled that many major firms had warned of economic disaster if the UK did not adopt the euro.
Margaret Thatcher”s former Chancellor said: “I don”t think their track record is all that great.”
And he condemned the Foreign Secretary Philip Hammond “rather shameful” for claiming that “if we leave, our former partners will try to punish us”.
He said: “There is no legal way in which they can do this, more importantly it wouldn”t be in their interest to do so.
“If we were to vote to remain in the EU, then they would indeed be able to punish us and it may well be in their interest to do so. There is seldom gratitude in politics.”
Lord Lawson, chairman of the anti-EU Vote Leave campaign, made the comments at the Royal Institute of International Affairs in central London.
His speech came days after David Cameron announced a referendum of Britain”s membership of the EU would be held on June 23.
He promised to hold an in/out vote after being elected as Prime Minister for a second term last year.