Password-protected Secret Burger at The Opera Tavern - NOW FINISHED

This is a new one to me, but it seems that The Opera Tavern offer a secret burger once a month to people who know the password.

Today's was announced with this tweet:

Tonight at Opera Tavern-January secret burger. Venison, iberico pork, cranberry relish and blue cheese. limited supply. pass word to follow.
— Salt Yard Group (@SaltYardGroup) January 11, 2012

Quickly followed by this:

Secret venison burger password-ask for Pierre the manager and tell him "I've got the horn".
— Salt Yard Group (@SaltYardGroup) January 11, 2012

& here's a picture of it:

Some restaurants have played games with items not on the menu for a long time - Starbucks and McDonalds both have items that you can (supposedly) order if you're in the know, and Honest Burgers in Brixton Village have the 'Federation Burger' in honour of their near neighbours Federation Coffee, but I think this is very clever because it's a 'one night only' thing.

When - Wednesday 11th January only

Where - Opera Tavern, 23 Catherine Street, London, WC2B 5JS

Map

Link - The Salt Yard Group on Twitter - follow them for future secret burgers!

Update - 20th January - they've done it again, to celebrate their first birthday:

Secret birthday burger revealed-remember "whats the quack?" duck, duck and more duck twitter.com/SaltYardGroup/…
— Salt Yard Group (@SaltYardGroup) January 20, 2012

Update - December 2021 - FoodSpotting (the Federation link) is now no more - this article explains the demise of FoodSpotting