AfD breakthrough: Is Germany on slippery slope after far-right triumph?

The first far-right party to win seats in the German parliament for 60 years.

Nazis in the Bundestag was the hyperbolic warning from the country's foreign minister. The AfD's historic breakthrough sent chills across Europe.

So did the pictures of its activists braying from a balcony with offensive hand gestures taunting outraged protesters gathered below.

Since World War Two German politics have been consensual and civil. Like partners in a solid middle class marriage, parties have kept their worst differences away from the public eye.

Boring, certainly, but given their pre-war and wartime history, that is exactly how Germans liked it. And it guaranteed stability and prosperity as Germany went from strength to strength.

That is about to change. AfD, or Alternative for Germany, are deliberately provocative, determined to be a thorn in the side of the German political establishment.

They have outraged Germany with posters unmistakably reminiscent of Nazi-era propaganda. Their ranks include neo-Nazis. Some have openly said it is time Germans stop being guilty for what the Nazis did during the war.

They use language that is intended to shock, for instance comparing immigrants with compost.

Their presence in parliament gives them a platform, staff and offices that will only establish them deeper in national politics. It will come as quite a shock given Germany's sleepy political traditions.

Nationally they gained almost 13% of the vote, but in former East Germany they won more than 20% and in Saxony more than 40%, making them its dominant party. Pretty astonishing for a party written off a couple of years ago.

Is Germany on a slippery slope now? Is the country full of closet neo-Nazis now unleashed and free to exploit their electoral success to become a major political power?

Or was this a protest vote? By voters fed up with their stale old politics and desperate for a change.

Polls suggest the latter. AfD drew voters from all parties and across the spectrum of German society.

Optimists concede the post-war consensus is over but that, they say, may be no bad thing. The right has been drawn out into the open and can now be challenged.

It is up to the country's mainstream politicians prove them right. Either way politics in Germany, predictable for so long, will never be quite the same.