It's genuine - The Sun has apologized!
See: http://mysun.co.uk/go/discussions/community.

ha! Well I hope they put their editors name up on the front page headline and demand a grovellng apology from him,for getting the name wrong...oh the irony!

Oh that's fantastic!

Reading back on the thread I was reminded of how the families of World War One were informed that their relatives had died.  It came in the form of a standard proforma letter, with spaces for the name of the dead person.  It was a form pre-signed and photocopied and it purportedy came from King George V in the form of 'His Majesty regrets, etc'.   And most families were informed by telegram that their relative had died.  Admittedly, with the sheer number of fatalities in the First World War, it is understandable that a personal letter to each family who had lost a loved one would not be feasible.  It was left to the dead soldier's CO (if he survived) to write a personalised sympathy letter to the devastated family.

Compare this show of sympathy then to the sympathy expressed by GB in his letter.  GBs letter was personal, he wrote it himself and obviously without the advice of any spin doctors surrounding him.  He probably did not tell anyone he was writing it even.  It came from the heart.  And it came from him personally.

The Sun has scored an own goal with this.  Anyone with any common sense could read the letter and interpret the genuine feelings of sadness contained within it.  Rather than make GB less popular, it will increase his popularity and show him to be a man with a natural and personal empathy towards a family who has lost a loved one.  My estimation of GB as a man, and as PM, has gone up rather than down after reading his letter.