Bingerle

That's the codeword for sex invented by Tsar Alexander II and his mistress in their letters to one another.

The enamoured pair often wrote to each other several times a day. They systematically numbered their love letters, signing off with the phrase: "With you always".

The letters were in French. But some sexual references were jotted down in Russian.

In 1871 Katia writes: "I saw in your eyes that you wanted to throw yourself at me to forget everything and enjoy our bingerle."

In another 28-page missive she reminds the Tsar that she is pregnant and urges him: "not to dare have any bad ideas and to remain untainted ... for I know you are capable in one moment when you want to make it (bingerle), to forget that you desire only me, and to go and make it (bingerle) with another woman."

The letters were auctioned off yesterday.