Too drunk to spot the difference - a valid defence?

On the 26th of February, The Daily Mail reported the case of Haydor Khan, a 22 year-old waiter who was charged with rape after going into a sleeping woman's room at a small hotel in Surrey and having sex with her.

Khan's defence was that he was too drunk to realise the woman wasn't his girlfriend.
Khan's girlfriend, according to the report, had already refused sex with him earlier in the evening because she was feeling ill.

For reasons best known to itself, the Daily Mail then tagged another report on the end of its account concerning a prosecution of a woman for making a false rape claim.
It should be stated here that rapes are depressingly common. False rape claims are rare, but they attract a disproportionate amount of press coverage.

A fortnight later, the newspaper followed up its report of Khan's acquittal with a piece from the point of view of the woman Khan had accosted. Joanne Freeman chose to waive her right to anonymity so the Daily Mail could report her anger and disbelief at the verdict.

She told the paper that "the verdict made her feel suicidal, adding: ‘It was excruciating telling a jury of strangers what happened. It has devastated the whole family. My father is heartbroken and my own daughter had to sit through the court case.’
"Her friend Karen Berry, 43, said Miss Freeman had ‘changed completely’, adding: ‘She is a shell of her former self. She tries to be strong but then you see she has a vacant look in her eyes or she breaks down.’"

So, from what we can gather from the two reports, a jury accepted that Khan's drunken belief he had the consent of the woman he "accidentally" had sex with, didn't constitute rape.

IS THIS REALLY JUSTICE?