The row that refuses to die descended into playground idiom when a Kremlin-funded news channel hit back on Friday at Prince Charles's alleged likening of Vladimir Putin to Adolf Hitler.

The pro-Russia broadcaster Russia Today (RT) regaled viewers with a mocked-up family tree linking royals to Nazis in a 'Takes one to know one' video poking the embers of the House of Windsor's German past.

"If anyone knows real Nazis it's the royal family" the channel declared on its In the Now programme while it flashed up sepia portraits of the Queen and family.

Here was Charles's great uncle, the Duke of Windsor, and wife Wallis Simpson, photographed visiting Hitler at his Obersalzberg retreat in 1937 shortly after abdicating as Edward VIII. Simpson, RT senior political correspondent Anissa Naouai solemnly pronounced, "hung out with Hitler".

There was the Duke of Edinburgh, his chest weighted with medals. "His sister, Sophie," added Naouai, "was married to a SS officer." Cue photograph of Christophe of Hesse-Cassel, marching in his SS colonel's uniform. Naouai could have added, for good measure, he named his eldest son Karl Adolf in Hitler's honour.

Then, the piece de resistance. Charles's "very own son" Prince Harry. Pictured in Nazi costume at a party on the front page of the Sun. "He likes to dress up as a Nazi, even if its just for Halloween," confided the presenter.

Which all goes to show: "Perhaps the royals are better seen not heard" and "Prince Charles should put his money where his mouth is".

The video attack comes three days after Charles precipitated a diplomatic row on tour in Canada when he spoke to a Jewish survivor of the second world war. In apparent reference to Russia's annexation of Crimea, he told Marianne Ferguson, 78: "Now Putin is doing just about the same as Hitler."

As Clarence House stressed it was "a private conversation" and deputy prime minister Nick Clegg defended the prince's right to espouse his views in private, Russia has refused to ignore the ensuing furore. The timing has been unfortunate, two weeks before Putin, the Queen and Charles join other leaders to mark the 70th anniversary of the D-Day landings.

Appalled at the Hitler comparison, Moscow's anger has been palpable. The Russian foreign ministry has declared: "These words, if they had been indeed uttered, are no compliment to the future British monarch."

The Russian ambassador had an urgent meeting with the Foreign Office which took place on Thursday.

During the meeting the Foreign Office appears to have brushed off Russia's complaint, saying it could not be expected to comment on private conversations. The failure of British officials to offer an "explanation" was described by the embassy as a matter of "regret".

This latest retaliation by Moscow will make uncomfortable viewing for a royal family which has, for almost a century, tried to put distance between it and its German roots by renaming itself Windsor in 1917.