Kaja Kallas will be giving up a lot to return to Europe to succeed Josep Borrell as the EU’s foreign policy chief.

Her 18th-century offices at the top of the picturesque old town in Tallinn marry elegance with efficiency, with the neoclassical cabinet chamber capable of projecting business papers on to the wall. Outside there is a balcony on the edge of Toompea hill where Kallas sometimes sits, with glorious views over the town and the Gulf of Finland.

But for the last…