The UK’s membership of the EU is “properly under way” and David Cameron is clearly delighted in the process of “reform and renegotiation”.
The PM was speaking in the early hours after formally setting out his aims to EU counterparts in Brussels.
He addressed EU leaders for 10 minutes at a summit dominated by the migrant crisis and Greek debt, although his exact speech was not reported.
The European Council’s Donald Tusk said there was a will to help the UK reports BBC.
However Mr Tusk, who is overseeing the membership negotiations, added that basic values “were not for sale”.
Mr Cameron wants to reform the UK’s membership of the EU before holding an in/out referendum of the British public by the end of 2017.
Broadly, Mr Cameron wants an opt-out on the core EU aim of “ever closer union”, and to boost the sovereignty and powers of national parliaments, so groups of them can block proposed EU legislation.
He also wants to safeguard the City of London and other financial centres outside the eurozone, to curb internal EU immigration by cutting benefits and to make the EU more streamlined and competitive.
Mr Tusk said talks would now start, before adding: “One thing should be clear from the very beginning: the fundamental values of the European Union are not for sale and so are non-negotiable.
“We should consider British concerns, but only in a way which will be safe for all of Europe. We’ll come back to this in December.”
The European Council defines the EU’s overall political direction and priorities.