The latest government risk matrices, visual aids designed to help civil servants and ministers make informed decisions on risks to the nation have shown the enormous threat of disease, which far outweighs that of terrorism, extreme weather, and widespread public disorder.

The danger of pandemic disease, including killer influenza, will be exacerbated in the coming two decades by growing microbial resistance to the drugs used to treat them. Simple ailments that can easily be treated at the moment could kill thouands in the near future – with the government estimating 80,000 could be killed in the United Kingdom in just one infectious event.

Death on such a scale in the United Kingdom is not without precedent – even in recent history. In the immediate aftermath of the Great War from 1918 onwards, a pandemic of flu killed 230,000 in just a couple of years, a fraction of the estimated 50 million killed worldwide.

The Daily Telegraph reports the prime minister David Cameron has warned the regression of modern medicine over the past century would cast Britain back into the “dark ages”.

The government document, the National Risk Register of Civil Emergencies, which is released to the public in reduced form but is available in full detail to senior ministers, and contains the most sensitive risk assessments and secrets of the state, also quantifies the risk of various forms of terror attack. The events are organised on two axis, one representing likelihood of happening in the next five years, and the other representing the level of impact a successfully attack would have.

While a ‘catastrophic terrorist attack’, a large-scale event on a similar level to the 9/11 attacks in the United States or worse, is rated as having the highest potential impact, it is also rated as having a ‘medium low’ chance of occurring. On the other hand, cyber-terrorism is has the highest-rated chance of taking place over the next five years, but the lowest potential impact.

More concerning is the rating of deadly terrorist attacks against transport systems in the UK, similar to the attacks against the London Underground and London buses. While the impact on the nation would be medium-to-high, the chance of a successfully attack in the next five years is the highest category.

Among other events that could ravage the United Kingdom, remarkably crises such as extreme snowfall and solar weather taking out electronic devices are rated to be as likely to occur, and as dangerous as terrorist attacks on public places.