Is Germany Cameron's key ally in EU debate?
Britain's Europe Minister has indicated that a referendum on British membership of the EU could come sooner than the deadline of 2017.
David Lidington also said he was optimistic that Britain could achieve reform of the EU.
One of the key players in that debate is Germany whose Chancellor Angela Merkel welcomed her French counterpart in Berlin for wide-ranging talks on Tuesday.
Katya Adler reports.