Produced in the late 1970s, "Protect and Survive" was the epithet of a pamphlet and twenty short Public Information Films (PIFs), published by the Central Office for Information of the British Government, providing advice to civilians of what to do in the event of a nuclear conflict.
The pamphlet was briefly made available then very rapidly withdrawn from sale, in light of ensuing public reaction ("your exercise in futility is to not run, try to get home, hide under (your bed) and please curl up and die quietly.").
The PIFs have never been deployed as intended. They were made for (and withheld from) general (repeated, continual) release onto (BBC) public television, in the event of the threat of a potentially nuclear conflict emerging.
Whilst the global nuclear scenario has changed (now more nuclear nations; bigger, improved and more numerous weapons), the immediate risks to people substantively haven't.
Nor have the fundamentals of the public advisements:
Don't try to run (mass panic, immediate roads gridlock and damage paralyses transportation infrastructure; maximum personal blast/radiation exposure results)
Hide (bury yourself as best you can for as long as possible)
The unspoken realities:
Many dense urban areas reside adjacent/close to possible military targets.
Nuclear weapons are profoundly indescriminate, use likely inferring considerable direct, collateral, civilian damage.
A nuclear attack could occur with very little notice (hence the infamous "four minute warning").
Today's active nuclear arsenals are massively more powerful than those that existed at the time these films were made.
The explosion of the Tsar Bomba (Царь-бомба, literally "Emperor Bomb", commissioned by premier Nikita Khrushchev) is shown towards the end of the presentation. This was the largest, most powerful nuclear weapon ever detonated in the history of humanity to date. Massively more powerful than any other weapon devised before or since, it was developed by the Soviet Union. The bomb was originally designed to have a yield of about 100 megatons (one hundred million tons) of TNT; however for testing that was reduced by half in order to limit the amount of nuclear fallout that would result. It was detonated on the 30th of October, 1961, in the Novaya Zemlya archipelago. The explosive power released was equivalent to ten times the total amount of all the explosives used in World War II, combined.The flash was seen 1000km away. The area of effectively complete destruction extended to 25 km, and ordinary houses subjected to severe damage out to 35 km. Windowpanes were shattered 900km away.Its explosion was approximately 4000 times more powerful than that of the Hiroshima bomb.
Though all other nuclear weapons have considerably smaller explosive yields, for technical reasons they produce proportionally more fall-out radiation effects.
The total number of fatalities from the relatively small Hiroshima bomb alone (not including the 140,000+ Nagasaki victims), including those from subsequent radiation effects, was over a quarter of a million people.
Modern weapons typically have yields ten to one hundred times greater than the Hiroshima bomb.
External fall-out radiation will likely remain at generally fatal levels for not less than 3-5 weeks.
The minimal, projected longer-term impacts upon health, water and power infrastructures, agriculture and fertility infer a further 60%+ loss of affected populations.
Any considerable nuclear exchanges carry additional risks of a subsequent nuclear winter occuring. Particulates thrown up by explosions and (urban/industrial) fires into the atmosphere causing long-term, significant reduction in sunlight reaching the surface, potentially lasting for years. The resulting chronic impacts upon food production alone would be likely fatal to more than half of remaining populations from starvation; with illness (both from the cold and from radiation/epidemic diseases) taking a large majority of the rest.