* Ex-finance minister Lawson: Britain better off out
* Says Cameron unlikely to win back powers from Europe
* Cameron under pressure over Europe before 2015 vote
* PM lauds "good day" for post-election referendum pledge
By Peter Griffiths
LONDON, May 7 (Reuters) - Britain should leave the European
Union because Prime Minister David Cameron's plan to claw back
powers from Brussels is doomed, a former senior minister said on
Tuesday, stirring divisions that threaten his party's
The intervention of Nigel Lawson, a heavyweight in the
Conservative party who served as Margaret Thatcher's finance
minister for six years, piles pressure on Cameron days after his
party suffered from a surge in support for the anti-EU UK
Independence Party (UKIP) in local elections.
Cameron came to power in a coalition government in 2010 with
a plea to his party to "stop banging on about Europe", an issue
that has divided the Conservatives for decades and helped bring
down two of his predecessors, Thatcher and John Major.
But, despite Lawson's comments highlighting that deep
divisions over Europe persisted within his party, Cameron said
it had been "good day" for his pledge to hold an "in-out"
referendum if he is re-elected in 2015.
"I welcome the attention that is being placed on this key
pledge," he told reporters. "I want to give people a proper
choice between Britain remaining in a reformed European Union or
leaving that European Union."
Lawson, finance minister from 1983 to 1989 and who now sits
in parliament's upper chamber, is the most senior member of
Cameron's Conservative Party to call for Britain to withdraw
from the EU.
Cameron's attempts to repatriate powers from Brussels would
probably only secure "inconsequential" results, Lawson said,
echoing warnings from France and Germany.
Britain would be better off outside a 27-nation bloc that
has become a "bureaucratic monstrosity", he wrote in Tuesday's
"I strongly suspect that there would be a positive economic
advantage to the UK in leaving the single market," Lawson wrote
in an article that stirred memories of a Conservative civil war
over Europe that raged for large parts of the 1980s and 1990s.
"In my judgment the economic gains would substantially
outweigh the costs."
Lawson, who voted to stay inside the EU's forerunner in
Britain's last referendum on Europe in 1975, said the euro zone
debt crisis had fundamentally changed the EU and he would choose
to leave if another vote was held.
More than 500 business leaders backed Cameron's
renegotiation policy in April, saying a new, looser relationship
with Europe would boost the British economy.
Others fear the referendum pledge has created years of
uncertainty that will deter foreign investment in Britain and
upset allies in the EU, Britain's biggest trading partner.
Cameron, trailing in the polls by around 10 points, supports
Britain's continued membership of a club it joined at the third
attempt in 1973. The latest YouGov poll found 43 percent of
voters would leave the EU and 35 percent would stay in.