Cameron cannot assume total support from Poland
Konstanty Gebert is a man gifted with an almost permanent chuckle.
Giving me a tour of his home, in Warsaw, once the town house of a Polish aristocrat, he mischievously speculates over the reasons for a floor-plan that separated servants from guests.
Then he tells me a joke, which did the rounds when Poland joined the European Union in 2004.
"Mr Kowalski [the Polish equivalent of Mr Smith], day after the accession, opens the windows of his flat, looks out: same pot holes in the road, same garbage strewn all over, same drunks sitting in the alley. 'Ah, what a mess they have in this EU. Was it worthwhile joining?'"
Mr Gebert starts chuckling again. The cynicism in that joke may offer some clue to the success of Law and Justice.
The centre-right political party won Sunday's general election, with 39% of the vote, becoming the first to win a parliamentary majority since the fall of Communism in 1989.
For UK Prime Minister David Cameron, the election gives him an important new ally in Britain's renegotiation of its membership of the EU.
Law and Justice is broadly Eurosceptic, and sits in the same grouping in the European Parliament as Mr Cameron's Conservatives.
So far, according to Foreign Secretary Philip Hammond, negotiations have been only a form of "shadow boxing" but after Poland's election "we're going to see the pace of negotiation accelerate quite sharply".
Mr Cameron's most difficult ask may be for some way of curbing migration from other countries in the EU.
When I suggest to Mr Gebert, the former editor of a centre-left Jewish periodical, that the new Polish government could help, the joking stops.
"Cameron will find an ally in sabotaging Europe if this is what he wants, but certainly not an ally in limiting freedom of movement within Europe... of Poles who want to go and work or live in the UK," he says.
This may seem surprising. After all, the Law and Justice election campaign included a tough line on the demand from Brussels that Poland admit refugees.
This is a notably homogenous country. In the 2011 census, 87.5% of people described themselves as Roman Catholic.
My visit to Warsaw brought home to me the symbolic power of freedom of movement within the EU for those living in the former Soviet bloc.
For Poles, getting a visa from a foreign country was the easy bit; the problem was getting permission to travel from their own government.
Witold Waszczykowski got out, and he wasn't allowed back in.
He was exiled to the US, he tells me, for challenging the Communist orthodoxy while teaching history.
A former career diplomat, he has been tipped to be foreign minister in the new government.
At the Sejm, the lower house of parliament, we discuss areas of potential agreement.
Both Britain and Poland have kept their own currency, so agree that there should be protection in EU decision-making to ensure they are not out-voted by those using the euro.
David Cameron also wants an exemption from the aspiration of ever-closer union.
On freedom of movement between EU member countries, and on curbing benefits for migrants, though, Mr Waszczykowski is clear.
"If you try to separate people, segregate them, and have different social benefits for those who live in UK and those who emigrated or stayed temporary in UK, this will be the problem," he says.
So the new government is unlikely to help Britain curb EU migration any more than the old one, which had bridled at the Cameron government's sometimes clumsy rhetoric about "Polish plumbers".
I am told by one of President Andrzej Duda's senior advisers that David Cameron has already held informal discussions with Jaroslaw Kaczynski, the leader of Law and Justice.
Mr Kaczynski is not a popular figure in either Berlin or Brussels. When prime minister, he seemed to delight in being an irritant to those running the European Union.
Five years ago, in a book, The Poland of Our Dreams, Mr Kaczynski suggested German Chancellor Angela Merkel would like to annex the areas in western Poland that used to be German.
"Merkel belongs to a generation of German politicians that would like to reinstate Germany's imperial power" he wrote, adding, "we could wake up to a smaller Poland one day."
Since he needs Angela Merkel's goodwill, Mr Cameron may be relieved that Beata Szydlo, rather than Mr Kaczynski, is the new prime minister, though few doubt the powerful influence the party leader of Law and Justice will continue to be.
Return to the conservative fold
If this new ally could also be a handicap to achieving a deal acceptable to Britain, there is one thing Mr Cameron might put on the negotiating table, a promise to return to the political family of Europe's principal conservative parties, the European People's Party (EPP).
A decade ago, frustrated by the EPP's federalist stance and to reassure his Eurosceptics, Mr Cameron took his party out of the grouping.
His MEPs are in the European Conservatives and Reformists Group, along with Law and Justice.
"Angela Merkel is known to be a patriot for the EPP," Radek Sikorski, Poland's former Foreign Minister, tells me.
Until last year, Mr Sikorski served in the outgoing government of Civic Platform, whose MEPs are in the EPP.
He says by not being part of the bigger grouping, the Conservatives are not "where many of the decisions are pre-cooked".
An offer to return would please Mrs Merkel, and might help in the choreography of renegotiation, providing Mr Cameron can convince his Eurosceptic colleagues that Britain will get something concrete in return.
But how would Mr Kaczynski react? On past political form, he can be a staunch ally - but he makes a terrible enemy.
Shaun Ley visited Poland for The World This Weekend, which is broadcast on BBC Radio 4 on Sundays at 13:00 GMT.
Full member parties of the European People's Party:
- Austria: Austrian People's Party
- Belgium: Christian Democratic and Flemish, Humanist Democratic Centre
- Bulgaria: Citizens for the European Development of Bulgaria, Democrats for a Strong Bulgaria, Union of Democratic Forces, Democratic Party, Movement "Bulgaria of the Citizens"
- Croatia: Croatian Democratic Union, Croatian Peasant Party
- Cyprus: Democratic Rally
- Czech Republic: TOP 09, Christian and Democratic Union - Czechoslovak People's Party
- Denmark: Conservative People's Party, Christian Democrats
- Estonia: Pro Patria and Res Publica Union
- Finland: National Coalition Party
- France: The Republicans
- Germany: Christian Democratic Union, Christian Social Union
- Greece: New Democracy
- Hungary: Fidesz, Christian Democratic People's Party
- Ireland: Fine Gael
- Italy: Forza Italia, New Centre-Right, Union of the Centre, Populars for Italy
- Latvia: Unity
- Lithuania: Homeland Union - Lithuanian Christian Democrats
- Luxembourg: Christian Social People's Party
- Malta: Nationalist Party
- Netherlands: Christian Democratic Appeal
- Poland: Civic Platform, Polish People's Party
- Portugal: Social Democratic Party, Democratic and Social Centre - People's Party
- Romania: National Liberal Party, Christian Democratic National Peasants' Party, Democratic Union of Hungarians in Romania, People's Movement Party
- Slovakia: Christian Democratic Movement, Slovak Democratic and Christian Union - Democratic Party, Most-Híd, Party of the Hungarian Community
- Slovenia: Slovenian Democratic Party, Slovenian People's Party, New Slovenia
- Spain: People's Party, Democratic Union of Catalonia
- Sweden: Moderate Party, Christian Democrats