Intelligence agency GCHQ has been forced to delete an online brainteaser after accidentally spelling out the c-word.
An answer to one of its regular puzzles had underlined the fourth letter in the names of the planets Mercury, Venus, Uranus and Neptune.
Twitter users were quick to point out the irony of the code-breaking body, famed for cracking the Enigma, missing such a glaring blunder.
One mocking follower tweeted: ‘Even the most brilliant code breakers can end up with a four letter blooper. See you next Tuesday perhaps?’
Another joked: ‘Was GCHQ accidentally sweary, or did they planet that way?’
Yesterday morning, GCHQ invited its 115,000 followers to solve the remainder of the sequence: C, U, T, S, I, U, N.
Revealing the answer as T – the fourth letter of the final planet, Neptune – it demonstrated the logic by underlining the fourth letter of four other planets.
But it failed to spot that its selection of Mercury, Venus, Uranus and Neptune spelled out the rude word.
GCHQ hastily removed the tweet within 20 minutes and amended the question to include the letters of all eight planets.
A GCHQ spokesman: ‘We apologise for any offence inadvertently caused by this morning’s post. We deleted it as soon as we became aware of the issue.’
Headquartered in Cheltenham in a ring-shaped compound known as The Doughnut, the UK’s top intelligence agency is steeped in history.
It is most renowned for cracking the German’s Enigma code during the Second World War, when it was based in Bletchley Park.
The agency itself is divided into an intelligence-gathering arm known as the Composite Signals Organisation, and the National Cyber Security Centre which shields the UK’s communications infrastructure.