An upcoming magnum vs bottle champagne tasting at Islington’s The Finest Bubble, led by wine critic Jancis Robinson, hopes to settle the question.

It is something even the world’s renowned wine experts can’t explain: the beguiling, near magical process that happens to champagne when it is aged in magnum.

In a bottle twice as large as normal, the evolution slows, and even the richest of Champagnes seems more opulent; yet the intricate differences between the two sizes have remained relatively unexplored. On October 8, Islington Champagne company The Finest Bubble are hoping to lift the lid on such complexities, as they invite one of the world’s leading wine critics, Jancis Robinson, to host a tasting night specifically focussed on bottle versus magnum or jeroboam (an even larger bottle at four times the regular size).

The night provides an opportunity to enjoy some of the rarest and most highly-acclaimed Champagnes in the world. Guests will be invited to taste 13 prestige cuvée Champagnes blind, casting their votes to see how the respective bottle sizes really compare.

“In the wine trade it’s always been one of these long established notions that magnums of Champagne always age better than a bottle, so that’s really where my idea came from,” says Nick Baker, managing director of The Finest Bottle, which he set up as an online ordering service a year ago.

“To show the differences between bottle and magnum, the Champagnes need more maturity as when they’re very young the differences aren’t going to be as great. So we have to taste vintages that aren’t too young to really see the big differences; hence the youngest we’re tasting is a 2002 vintage, and the oldest a ‘96.”

In more than 40 years as a wine critic, Robinson admits she has never had the chance to carry out a “proper comparison of Champagne aged in bottle versus the same wine aged in magnum”. The main problem, Baker explains, lies in finding such rare bottles of the same age and grape, and it has taken him the best part of a year to bring this event together.

Having carried out a preview tasting of 1998 Krug, he and Robinson were surprised by the results. Presented blind with the Champagne and magnum, she noted one glass had a markedly “youthful” taste, but was stunned to find it was the magnum. “This is a discovery,” admits Baker. “We don’t know how it’s going to go. We’ve got a clue from the preview, but there’s lots of little subtleties we probably will discover. Are the younger vintages less far apart or the older vintages much further apart?”

At 67 Pall Mall on October 8. Visit thefinestbubble.com.