The production method devised by the famous 19th century famous houses to make Champagne are still used today. The first fermentation produces a still, acidic wine.

Before it is bottled, a small measure of wine, sugar and yeast is added. This is known as the 'liqueur de tirage'.

The bottle is then sealed and the liqueur sets off a second fermentation, with the resultant carbon dioxide bubbles trapped inside.

The bottle is set upside down and turned at regular intervals to shake the yeasty deposits down into the neck.

This process is known as 'remuage'. At its end the bottle neck is frozen and the bottle is opened to allow the plug of icy sediment, known as lees, to shoot out.

The bottle is then topped off with a small amount of still wine and sugar solution, known as 'liqueur d'expédition' and resealed.

The amount of sugar used at this juncture determines whether the Champagne is Brut (very dry), Sec (less dry), or Demi-Sec (semi-sweet).