British Prime Minister Boris Johnson is meeting Dr Ursula von der Leyen, president of the European Commission - the European Union's top executive body - in London today for the first talks of the year about Britain's future relationship with Europe after the British leave the EU at the end of this month.

Both leaders want the meeting to go well. Mr Johnson hopes a cordial encounter in London today will set a productive tone to the trade discussions that will follow over the course of the year.

And although Dr von der Leyen will not be negotiating specific policies with Mr Johnson today, she is fully aware that forging a personal bond with him remains an important objective for the union. Still, the political interests of both leaders pull them apart.

Almost four years after the British narrowly voted to leave the EU, a consensus has finally emerged in London over how this will be done.

Mr Johnson's decisive electoral victory last month means that Britain will put an end to almost half a century of EU membership by leaving the union on Jan 31 at 11pm London time.

Some of Mr Johnson's fervent anti-Europeans want to transform this day into a carnival. Mr Mark Francois, a prominent backbench MP, is introducing a parliamentary motion this week asking for London's iconic Big Ben clock - currently under repair - to chime the moment Britain leaves the EU, "to provide an appropriate national focus for this truly historic event", as he puts it.

But such irrelevant fripperies aside, it is clear Mr Johnson will get his separation legislation through Parliament by the end of this week without a hitch and that the period of confusion which prevailed in London is now truly over.

With an overall government majority of 87 MPs over all opposition parties, he has the freedom to do more or less as he wishes. However, the snag is that the act of leaving the EU is but a prelude to the much more serious negotiation about Britain's future trade deal with the union.

And here, instead of allowing himself maximum room for manoeuvre, Mr Johnson has constricted himself by insisting that all the trade talks should be completed by the end of the year, when the current transition arrangements which allow Britain to continue to trade with the EU as a member until the end of December expire.

"His message will be that we need to crack on with the process," said a spokesman for the Prime Minister in briefings for the media on the eve of today's meeting with the European Commission president, adding that Mr Johnson did not want to be drawn into a "pointless argument" about whether the transition period was going to be extended.

But Dr von der Leyen remains sceptical about the ability of either side to finish such complicated negotiations in only 11 months. In media interviews on the eve of her London trip, she urged the British government to ponder the fact that "an extension to the talks is needed".

In many respects, the dispute about the time framework is just a prelude to a much more serious disagreement about what the trade talks should include. Mr Johnson is interested only in negotiating a deal that avoids the introduction of tariffs and quotas on manufactured goods between Britain and the EU.

That would still leave other Customs-related rules and regulations governing the trade in services such as finance and insurance products in place between Europe and Britain, because he wants his country to remain free to compete with the EU in such sectors, where the British enjoy and hope to retain competitive advantages.

Britain, for instance, has a banking sector which dwarfs the rest of the EU's and is around three times the size of either Germany's or France's; Mr Johnson wants this protected from EU regulations.

But Dr von der Leyen, a former senior German politician, would be only too aware of opposition to such "cherry-picking" between trade and services from key European governments.

In a speech at the end of last year, German Chancellor Angela Merkel warned that her country "will have an economic competitor at our own doorstep, even if we want to keep close economic, foreign and security cooperation and friendly relations with Britain". And the competition which the Germans and French - among others - fear most is precisely over services.

The result is that, at least for the moment, there is no agreement on the format of the talks and the sequence of the negotiations, let alone their substance. The first encounter between the British Premier and the EU's top leader is unlikely, therefore, to herald the start of a beautiful relationship.