David Cameron has only ever said he would look at "alternatives" to his four year ban on benefits for EU migrants - if those countries opposed to the ban could find one.

On Friday, in Prague, we got the first confirmation of what what one of those alternatives actually is: an emergency brake on migration.

Confirmation came from the Prime Minister of the Czech Republic in a press conference with David Cameron.

It would allow EU countries to temporarily close their borders to incoming workers if the pressure of migration has become too great.

For the leaders here in Central Europe, that change seems to be preferable to the ban on benefits which would discriminate between their citizens working in Britain and those who are already British citizens.

We don't know what an emergency brake would look like.

How would it operate?

Who would decide if and when the pressure of migration has become too great?

Is it simply a temporary solution to a permanent problem?

And doesn't an emergency brake on migration break that fundamental pillar of the EU of which we have heard so much: the free movement of workers?

And for that reason, it might meet even greater opposition in other parts of this 28-member Union than Mr Cameron's plan for a ban on benefits.