We're late on this -- but apparently, a British diplomat was ordered out of Russia in a tit-for-tat expulsion. Moscow calls the ejection from its London embassy of a Russian diplomat as groundless. The UK Foreign Office insists there is 'clear evidence' of spying.
Via the Guardian:
The mutual diplomatic expulsions between Russia and Britain are the first since 2007, when Kremlin critic Alexander Litvinenko was killed in London with a rare radioactive isotope.
"The British side took an unfriendly step the other day, having groundlessly declared one of our colleagues in our embassy in London persona non grata," Russia's foreign ministry said in a statement.
Active links added above. I bet you, neither side bothered to buy Christmas wrappers and ribbons or wrapped their PNG'ed gifts for the holidays.