Under the Russian Orthodox liturgical calendar, Christmas is observed on 7 January.

Mr Putin was visiting his home town of St Petersburg when he pulled the trigger on a howitzer at the Petropavlovsky Fortress on the banks of the Neva River.

The gun fires a daily midday salute, a tradition since 1865.

The Russian president’s steely image was in full force for the event: bareheaded in the winter cold, he appeared to flinch only slightly when the cannon released its power, then turned away with a smile.