(TheGuardian) - The collection, stashed beneath the floorboards of the Beaufort-Spontin family’s Becov castle, could fetch almost £1m.

They sat beneath the floorboards for decades – silent, fermenting witnesses to aristocratic opulence, Nazi rule, cold war espionage and American fortune hunters.

But Czech authorities have discovered a 150-year-old wine collection secretly stashed in a medieval Czech monastery after the second world war and found almost 40 years later is now worth more than €1.1m (£840,000).

The 133 bottles of wine, which date mostly between 1856 and 1899, once belonged to the wealthy Beaufort-Spontin family who lived in Becov castle, but fled to Belgium after the war ended, accused of being Nazi sympathisers.

Before the family escaped, they stashed the valuable wine under the floor of the chapel to keep it from plundering solders – and possibly with the hope of one day returning for their collection.

But after the Czech government, who had taken possession of the monastery in 1946, was given a tip-off that valuable treasures were hidden in the house, authorities began searching the property and stumbled upon the cache of buried wine.

The 133 bottles had remained, forgotten, in state possession since 1985 but interest in the wine was recently renewed after a decision to put it up for auction.

Greg Lambrecht, the creator of Coravin – an instrument which can test aged wines without fully opening them – was invited to taste the bottles, deem them drinkable and validate their quality.

Lambrecht was given 14 bottles to test – some labelled and others a mystery – and described the experience of drinking 150-year-old wine as “extraordinary”, with some bottles “truly life-changing”. In order to make sure he did no damage to the lavish bottles, Lambrecht even designed a special version of his Coravin tool, with an ultra thin needle to pierce the cork.

He said: “These wines were in pristine condition, they were all perfect. From the first glass to the last that I poured my hands were shaking. They are an encapsulation of history; this wine has lived through two world wars, was seized by a communist government from a fascist government from a monarchy before that and are now released in a democracy. And literally, they were the best wines of my life.”