Unfortunately, they all identified the wrong Martyn Smith.
The Mirror published the following apology:
Yesterday, due to an error in copy supplied to us, we identified the wrong Martyn Smith in an article entitled "BBC paedo let off jail".
We mistakenly stated that the BBC producer behind Dragons' Den had been convicted of having 1,410 repulsive child porn images.
He had not and we apologise to him for the distress and embarrassment caused by this mistake.
The Martyn Smith who was convicted is a former BBC producer.
But this apology no longer appears to be on the Mirror's website, nor does the Telegraph's, although it's not clear why either has been removed.
The Mail, Belfast Telegraph and Brighton Argus all still have their apologies to Mr Smith online. But if you Google Smith's name and the allegation, there are still results visible which repeat the error (even if the articles have indeed been removed) so none of the clarifications should have been taken down.
The false claim appears to have started with the Press Association, who have also unreservedly apologised.
But shouldn't all these other news outlets have checked their sources before mindlessly copying-and-pasting such a serious mistake?