It’s a dinner party game. If you’re having dinner with serious wine geeks I should add, but probably don't need to.

Many might say the 1855 classification was the most significant moment in Bordeaux’s wine history, but Jane Anson argues a much more important – and subtle – shift took place at the start of the 1970s.

Let’s call it, for argument’s sake, ‘the day that changed Bordeaux‘, but feel free to substitute Bordeaux for Napa, the Rhone, Burgundy or Barossa – as your friends and tolerance for arcane wine trivia permit.

I’ll get us started with Bordeaux, because it just happens to be my particular specialist subject. The idea is to think of events that defined the region and decide which one best contributed to the place that it is today.

The Bordeaux Contenders

  • Eleanor of Aquitaine

Clearly we could start with 18 May 1152, when Eleanor of Aquitaine married Henry, Duke of Normandy, who became King of England two years later. The marriage took place in Poitiers eight weeks after the annulment of her first marriage, although Bordeaux gets a look in, because some records say she stayed at Chateau Lafite in the proceeding weeks, and others that Chateau d’Issan was served at the wedding). This was the moment that made Aquitaine a duchy of the English crown, and without a doubt Bordeaux wine would not taste the same today, or be so widely distributed around the world, without it. But it seems lazy to name a 1,000-year-old marriage as the most significant moment in shaping what Bordeaux is today.

  • 1855 and all that

We could consider April 18 1855, when the Chamber of Commerce and Industry of Bordeaux was presented with the first version of the 1855 ranking by the Bordeaux brokers’ union – minus Cantermerle, which was added in September of the same year. Or, fast forward to 21 June 1973, when Mouton received the letter officially confirming that it had been promoted to a first growth. But, the 1855 classification is still a little too far back in history to really shape the landscape today, and limiting ourselves simply to classified Bordeaux misses the point of the game. Events affecting 1855 Bordeaux, no matter how monumental for the fine wine market globally, affect only a small percentage of the output of Bordeaux as a whole.

  • Robert Parker and Bordeaux 1982

So, how about 23 March 1983, when Robert Parker Jnr flew back to the US after tasting the Bordeaux 1982 en primeur wines? This was the moment when he determined to call the wines the best he had tried, setting off the reputation of 1982 as the vintage of the Century, and leading to the unstoppable (or so it seemed) rise in the en primeur system, and the hegemony of the 100 Point scale.

  • 1976 Judgement of Paris

Or, there is always 24 May 1976, when Steven Spurrier – now Decanter consultant editor – held a small wine tasting at the Intercontinental Hotel in Paris that pitted top growths of Bordeaux and Burgundy against some pretenders from California. The result was the now infamous Judgement of Paris, where California Chardonnays took three of the top four spots in the white wines, and a Napa Cabernet Sauvignon headed the list of reds. Arguably, the effects were greater in California than Bordeaux. Last time I visited California, in 2014, I was fascinated by how many wineries had copies of George Taber’s book on the tasting in their boutiques.

But, the tasting will also have played its part in waking Bordeaux up to the realities of New World competition. Besides a host of wines that we may not otherwise have had such as Opus One and Dominus, there’s no doubt that it started a shift in attitude towards ripeness, tannins and a host of new techniques in viticulture back in Bordeaux.

  • China

If we are really looking at shaping the modern landscape, I might suggest 29 October 2010, when the arrival of China to the Bordeaux fine wine table was announced with a bang. This was the date of a Sotheby’s auction held on a Friday night at the Mandarin Oriental in Hong Kong selling ex-cellar Chateau Lafite Rothschild dating from 2009 all the way back to 1879 – so pre-phylloxera, which is another event that we could have found a date for.

China has certainly affected Bordeaux at every level; in price terms, arguably only for the prestigious estates, but for everyone in terms of export destinations, real estate values (and likely neighbours) in some of the smaller appellations and stop-over spots on sales trips. And the date that I am going to choose does have an impact on the Chinese love affair with Bordeaux, but in a slightly tangential way.

But the winner is…

The date I am choosing is little known, but it is one that affected every winemaker within Bordeaux at the time, and certainly has a direct impact on its global image today; 15 December 1970.

This was the day that the harvest declarations for the year were published. Winemakers had to submit them a few weeks earlier to their local unions, which verified and publicised them. In 1969, white wines accounted for 59% of all declared harvests by winemakers across the region, compared to just 41% of red. But, in 1970 and for the first time, the red wine harvest surpassed that of the whites – 2,060 million hectolitres of red compared to 1,303 million of white, so just over 60% red. The colour change in the Bordeaux vineyard had just passed the point of no return.

Like many of the other suggestions here, the impact was probably little noted at the time, but this was a big change. As recently as the 1950s, Bordeaux was producing 60% white wine. And if you go back to the time of Eleanor of Aqutaine and right up the 1500s, certain regions such as St Emilion were pretty much pure white wine producers.

Today, the figures are remarkably different; 90% red wine and just 10% white. And the reduction of the white vineyard may not be over. Despite the quality of this style of wine being higher than ever, white production has dropped by one further percentage point in the last 10 years.

Since then, it’s the red wines that have attracted new markets such as China, it’s the red wines that are renowned for the structure and ageing abilities that gives Bordeaux its identity, and it’s the red wines that form the vast majority of the turnover.

But, what I like about the change that was signalled during December 1970 is what it reveals about the psychology of Bordeaux. We think of this as a place that has remained frozen in time, the most traditional of all wine regions, governed by events in 1152 and 1855. To perform an almost 90-degree turn in production from 1950 to 1970 is pretty incredible (and 10 years later, by 1980, we were approaching today’s percentage dominance of reds). The turnabout was brought on by a series of devastating frosts, by an economic crisis that highlighted the dangers of relying on a wine style that would not improve in the cellars while waiting for the market to pick up, and a response to the global rise in appreciation of red wine.

It shows an understanding of market opportunities that will not surprise anyone who knows the Bordelais, and a flexibility of spirit that might come as more of a surprise. On 15 December 1970, the Bordelais showed that they are more than capable of admitting when they’re wrong.