Italian newspaper L'Espresso [repubblica.it] requested documents from the UK and Sweden using Freedom of Information Act (FOIA) mechanisms and while they didn't get anything from the UK Crown Prosecution Service they did get 226 pages from the Swedish Prosecution Authority, enough to cast some light on what went on behind the scene.
From their English [repubblica.it] version (original in Italian [repubblica.it]):
The files obtained under Foia reveal that from the very beginning, the "Crown Prosecution Service" in London advised the Swedish prosecutors against the investigative strategy that could have led to a quick closure of the preliminary investigation: questioning Assange in London – as he has requested on many occasions - rather than extraditing him to Stockholm, as the Swedish prosecutors have always tried to do.
In January 2011, not even two months after Julian Assange had been arrested in London, a lawyer at the Crown Prosecution Service, Mr. Paul Close, strongly advised the Swedish magistrates against questioning the WikiLeaks' founder in London.
Much more in the L'Espresso news articles including some of the documents. There's also coverage (so far) by 9news in australia ("Details in new UK documents stun Assange" [9news.com.au]) and RT out of Russia ("UK resisted Swedish efforts to interview Julian Assange" [rt.com]).