Extract from John Rentoul Blog:

According to a remarkable PhD thesis by Rebecca Lewis:

‘Keep Calm and Carry On’ was printed and held in reserve for when the necessity arose, for example, a severe air-raid, although it was never actually displayed.

Lewis does not say why it was held back. It may be that the tone seemed right before the German tanks rolled into Poland, but that, once the war had actually begun, it lacked the sense of urgency demanded by the premonition of total war.

But she does quote from contemporary evidence that the two posters that were used were widely disparaged. According to Mass-Observation:

‘Your Courage’ was the second most-mentioned remembered slogan … it still existed everywhere, and was deemed mostly annoying and inappropriate for the wartime situation. The wording of ‘Your Courage … will bring us victory’ was criticised. There was some evidence the combination of ‘your’ and ‘us’ ‘suggested to many people that they were being encouraged to work for someone else’, with the ‘your’ referring to the civilian, the ‘us’ to the Government … ‘Freedom is in Peril’ was also deemed ineffective, blamed on ‘the abstractness of the words, not one of which had any popular appeal’.

“Freedom is in Peril” has also enjoyed a bit of postmodern popularity, partly in the wake of the “Keep Calm” fashion. But it wasn’t taken at face value at the time:

The Times had described the posters as ‘egregious and unnecessary exhortations’, ‘insipid and patronising invocations’, which were unneeded and wasteful of funds, comparing the posters unfavourably to those produced by the French.

Read the full blog entry.

Note: Yes, I am catching up on the summer’s Google Alerts!