Ten minutes warning, if that, is all the UK population would have to prepare for a nuclear attack.
An intercontinental ballistic missile carrying a nuclear warhead would take only 20 minutes to travel from Russia to Britain before exploding with a force equivalent to 1,000,000 tons of dynamite.
As Russia has updated its doctrine to lower the threshold for using nuclear weapons and British Storm Shadow missiles were fired into Russian territory for the first time, this threat seems more likely than ever.
If a bomb of that size were to hit central London tomorrow, an estimated 1,050,720 Londoners would die and 2,489,210 people would be injured, according to nuclear modelling website NukeMap.
Up and down the capital – from Camden in the north and Brixton in the south to east London’s Canary Wharf – residential buildings would collapse, injuries would be universal and fatalities widespread.
Third degree burns would be sustained far out as Richmond, Wood Green and Wembley.
Even if you were to live further than 12km from the hit point, you are still not safe.
Many that far out will see the flash of the nuclear explosion and run to the window, only to be injured by the shattering.
What do you do when you are told of a nuclear strike?
Within 10 minutes of Russia launching a nuclear strike, news channels and radio stations will start broadcasting an emergency warning to the public to seek shelter.
With five minutes to go, the Home Office would send a signal to every British mobile phone to warn people of the incoming threat saying: ‘BALLISTIC MISSILE THREAT INBOUND. SEEK SHELTER.’
The safest place to go in that narrow space of time is the basement of a large, multi-storey concrete building.
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However, if that is not possible, run for the most structurally integral point in a building, such as the central staircase in a block of flats, away from exterior walls.
Alternatively, the government recommended in 1980 that families seek shelter in kitchen cupboards.
There is a longer list of places to avoid at all costs: wooden structures, such as sheds, tall furniture, long corridors and hallways are likely to amplify the dangers of a nuclear strike.
It is crucial to protect your body from the ‘thermal pulse’, a blast of heat energy that emanates from the bomb. To do this, lie face down with your arms and hands tucked under your body.
If you have to time to change, then get into pale colours that will reduce the risk of catching fire by reflecting the thermal pulse.
Finally, close your eyes and do not look at the blast or you risk being blinded by the ‘atomic flash’.
Do not be fooled by the first flash either, keep your eyes closed as a second one will appear quickly after, as light previously trapped behind the bomb’s ‘shockwave’ escapes.
What do you do after a nuclear bomb has exploded?
It takes 10 to 12 minutes after a nuclear explosion for the lethal radioactive fallout will begin raining down.
The government currently recommends: ‘Go in. Stay in. Tune in.’ But others might want to make a dash for it in hopes of avoiding this fallout, which could stretch as far as 250 miles from the blast.
Electric cars, however, will be rendered useless by the electromagnetic pulses of the blast and many conventional cars will have turned into scraps of metal.
If your car is still functioning, then travel upwind, or cross-wind, away from the fallout.
If you choose to remain in your shelter, you need to stay inside at all costs and secure your hideout from the incoming radiation.
Seal off conditioning units and fireplaces and cover door frame gaps with gaffer tape.
Whether you are running from radiation or barricading yourself in a safe shelter, everyone should cover their nose and mouth after a nuclear explosion, either with a cloth or, if to-hand, a P2-grade face mask.
Wear glasses or goggles and stick cotton wool in your ears while also covering any open wounds.
It will be safe to come out after two weeks, by then the radioactive fallout will stand at only one per cent of its original strength.
How do you decontaminate yourself?
Shower with warm water and soap.
Shampoo can be used to clean hair, but conditioner, body lotions, creams and moisturisers are strictly forbidden, because they contain ‘cationic surfactants’ that trap and bind radioactive particles to the body.
To get rid of radioactive dust inside the ears and eyelids, where it tends to settle, use a damp cloth and scrub under your fingernails. Blow your nose gently, also.
Any used towels or clothes must be promptly sealed away and discarded.
What can I eat after a nuclear strike?
On the menu are: iodine-rich foods include seaweed and potato peel.
The thyroid gland is the most susceptible organ to damage from radiation, so taking iodine tablets would be ideal to protect yourself against thyroid cancer.
Bottled water is also your friend; it should be rationed carefully.
Tap water must be only be drank as a last resort and only after being filtered through clay soil, if possible.
Any tinned foods, such as beans and soft fruits, may also contain water that is safe to consume