I went to Budapest last year and did the usual touristy things. I climbed up the hill to the fantasy castle walls in Buda. I took a boat ride. I went to the Turkish baths — edging cautiously into scalding hot water and then summoning up the courage to tip a bucket of cold water over myself.

Finally, I reached the grim end of the tourist trail: the so-called House of Terror. On the outside, it looked like every other Hungarian house on the boulevard. Inside, it was a museum set up in the actual place where first Nazis, then communists, inflicted imprisonment, terror and murder. Visiting it was a powerful emotional experience. You see the actual basement cells where prisoners were tortured or hanged. There was a ‘standing cell’ with no room to sit down, where prisoners were beaten if they even leaned against a wall. My girlfriend found it so overwhelming that she had to be helped out. Not by me, I am afraid. I had gone ahead and was too engrossed to notice she was in difficulty.

I learned many things I did not know. From Hungary, 600,000 people were taken to work camps in the Soviet Union and half did not return, dying of maltreatment and starvation. There were videos of some of the survivors talking about the horrific way in which they were treated. Of course, I had heard about the millions of deaths that took place in the Soviet Union at the hands of Stalin. Since I have returned, I have discovered that there were mass deaths across the Eastern bloc.

The visit haunted me and recalled to my mind the millions of people who were killed in the Far East, particularly in China under Mao Tse Tung. It also brought to mind the mass murder in Cambodia under the communist regime known as the Khmer Rouge, and in communist Vietnam. And, of course, the terror in North Korea continues to this day. Put this all together and you come to realise that, across the world, the biggest man-made disaster of the 20th century was the terror and death inflicted by communist regimes.

But is this widely recognised? No. Is it taught in our schools? No. Are there museums to remind us about it? No. The one I visited in Budapest is an isolated case which was set up in the face of considerable opposition.

If I talk to my children and their contemporaries they know nothing about the extraordinary death toll. The historian Robert Conquest estimated that the total number of lives lost during the terrors perpetrated in the USSR could ‘hardly be lower than some 13 to 15 million’. But it could be much higher. The deaths under communism in China seem to come in three phases: the suppression of counter-revolutionaries (at least one million); the ‘Great Leap Forward’ (at least 45 million), and the Cultural Revolution (750,000 to 1.5 million in rural China alone). In Cambodia, it is estimated that between 1.4 and 2.2 million, from a population of about 7 million, were killed. Add all these deaths together and some historians estimate as many as 100 million have died from communism alone.

But awareness of this is fading. The generation that has grown up since the collapse of the Berlin Wall does not seem to understand the connection between communism and terror. Today, they are able to think that communism is the ultimate form of egalitarianism, a perfectly amiable ideology. In Britain and America, the far left is experiencing a surge of popularity.

The future of any civilisation is shaped by its understanding of the past. That is why we consider it important to create museums of the Holocaust to remind us of the evils of anti-Semitism. You find them in Germany, Poland, the Czech Republic and elsewhere. Last year, David Cameron announced that a national Holocaust memorial and learning centre would be built in London, with the government contributing £50 million to the cost.

Perhaps we should also create a permanent reminder of what communism did to humanity and could potentially do again. I would like to suggest that a Museum of Terror be created in London, too. If supported by MPs, covered by the media and visited by parties of schoolchildren, it could help ensure that background knowledge of comrades Stalin, Mao and Pol Pot was as widespread as awareness of Hitler and Churchill.

But if we are to create such a museum, we need to start quickly. For me, the video testimony of survivors was the most powerful exhibit in Budapest. Such testimony needs to be gathered from around the world while those affected are still alive. In order to put together such exhibits we would need major donors. And the need for this is pressing. If we do not create it, all this will be forgotten.

Add all the deaths together and some historians estimate that communism has killed as many as 100 million

James Bartholomew is the author of The Welfare of Nations and coined the term ‘virtue signalling’ in this magazine.