Here are the lyrics from Bringing the News from Nowhere, which are just a bit different from those that Bill SDables posted. The book doesn't have an alphabetical index, so sometimes my weary eyes miss things.

Stand Firm
(Leon Rosselson)

Don't cower like a shower when the clouds begin to loom,
STAND FIRM! STAND FIRM!
You will have a good four minutes to prepare your refuge room,
STAND FIRM! STAND FIRM!
For our Early Warning System will be broadcasting the news
So don't sprawl around Trafalgar Square or lounge about the loos.
(And switch off all electric fires sos not to blow a fuse)
STAND FIRM! STAND FIRM!

You will leave your bingo sessions, push aside your plates of chips,
STAND FIRM!
Pull your socks up, jut your chins out and button up your lips,
STAND FIRM!
When you've turned off all your tellies and abandoned all your beers,
Consult your local warden who will help allay your fears,
(To deaden the explosion, put your fingers in your ears)
STAND FIRM!

A slit trench will protect you from the fallout and the blast,
STAND FIRM!
And don't emerge from hiding while the radiation lasts,
STAND FIRM!
To prove to the aggressor that free men will be free,
Crouch down in your hidey-holes, make lots of pots of tea,
(If you're caught out in the open, duck behind a tree).
STAND FIRM!

So don't huddle in the rubble when the bombs begin to burst,
STAND FIRM!
There will be no need to panic; if the worst comes to the worst,
STAND FIRM!
You can make your contribution if you only keep your head, Try sweeping up the fallout, decontaminate the bread, But whether rescuing survivors or burying the dead,
STAND FIRM!

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Makes me think of the UK Emergencies Leaflet thread.
-Joe Offer-