Social networks erupted on Tuesday as people shared the terrifying message the BBC would have broadcast in the event of a nuclear attack.
While the script, written in the 1970s, was first released in 2008, it didn't stop thousands of people sharing the link between themselves some four years later.
But why now? Perhaps the nuclear tension with Iran has driven people to reconsider if they should be preparing to duck and cover? Or maybe hearing the government's plans for drought in the south east have made us wonder how much worse it could get?
Either way, we've copied the full text of the memo for your reading pleasure/terror below.
But remember - in the event of a nuclear attack the best thing to do is head to Switzerland - or rather to live there already - where maintaining nuclear shelters is mandatory for local governments.
BBC Nuclear Memo
This is the Wartime Broadcasting Service. This country has been attacked with nuclear weapons. Communications have been severely disrupted, and the number of casualties and the extent of the damage are not yet known.
We shall bring you further information as soon as possible. Meanwhile, stay tuned to this wavelength, stay calm and stay in your own homes.
Remember there is nothing to be gained by trying to get away. By leaving your homes you could be exposing yourselves to greater danger.
If you leave, you may find yourself without food, without water, without accommodation and without protection. Radioactive fall-out, which follows a nuclear explosion, is many times more dangerous if you are directly exposed to it in the open. Roofs and walls offer substantial protection. The safest place is indoors.
Make sure gas and other fuel supplies are turned off and that all fires are extinguished. If mains water is available, this can be used for fire-fighting.
You should also refill all your containers for drinking water after the fires have been put out, because the mains water supply may not be available for very long.
Water must not be used for flushing lavatories: until you are told that lavatories may be used again, other toilet arrangements must be made. Use your water only for essential drinking and cooking purposes. Water means life. Don't waste it.
Make your food stocks last: ration your supply, because it may have to last for 14 days or more. If you have fresh food in the house, use this first to avoid wasting it: food in tins will keep.
If you live in an area where a fall-out warning has been given, stay in your fall-out room until you are told it is safe to come out. When the immediate danger has passed the sirens will sound a steady note. The "all clear" message will also be given on this wavelength. If you leave the fall-out room to go to the lavatory or replenish food or water supplies, do not remain outside the room for a minute longer than is necessary.
Do not, in any circumstances, go outside the house. Radioactive fall-out can kill. You cannot see it or feel it, but it is there. If you go outside, you will bring danger to your family and you may die. Stay in your fall-out room until you are told it is safe to come out or you hear the "all clear" on the sirens.
Here are the main points again:
- Stay in your own homes, and if you live in an area where a fall-out warning has been given stay in your fall-out room, until you are told it is safe to come out. The message that the immediate danger has passed will be given by the sirens and repeated on this wavelength.
- Make sure that the gas and all fuel supplies are turned off and that all fires are extinguished.
- Water must be rationed, and used only for essential drinking and cooking purposes. It must not be used for flushing lavatories.
- Ration your food supply: it may have to last for 14 days or more.
We shall repeat this broadcast in two hours' time. Stay tuned to this wavelength, but switch your radios off now to save your batteries until we come on the air again. That is the end of this broadcast.