- By ITV News correspondent Angus Walker
The link between the 'rendition' of Abdul Hakim Belhaj and Tony Blair's infamous meeting with Colonel Gaddafi in 2004, the so-called 'deal in the desert', is crucial.
To an extent the delivery of Mr Belhaj into the hands of Gaddafi's jailers and torturers was a 'gift', a goodwill gesture to get the agreement that would see Gaddafi give up his WMD intentions and return to the international fold.
Today, I'm told Mr Blair, despite calls for him to also apologise from some Conservative MPs, is very "unlikely" to make any statement about today's unreserved apology.
Jack Straw, who was the Foreign Secretary at the time, has issued a statement saying that he "sought to act at all times" lawfully, but adding that he had "limited recollection" of the events although he'd "ascertained" he had given the verbal go-head for "some information to be shared with international partners".
For years, especially post 9/11, there's arguably been collective official amnesia when it comes to the UK's role in so-called 'rendition'. The few MPs who consistently raised questions in Parliament were, in the past, accused by Jack Straw and other ministers of coming up with conspiracy theories. So today's unprecedented formal apology is seen by them as, finally, an admission of the truth.
It's worth thinking about whether today's apology would ever have been made had that secret fax from the MI6 Director Mark Allen not been found in the ruins of Tripoli after the fall of Colonel Gaddafi. It was the 'smoking gun' linking MI6 with the "delivery" of Mr Belhaj and, from then on, undermined official denials.
More broadly speaking, today was not just a legal matter. Yes, the case against MI6, Jack Straw and the government has now been dropped. A personal hand-written apology from Theresa May handed over. Six years of litigation is over, but this murky episode is much more about the lasting effect on Britain's moral authority.
Over the years, during numerous conversations with security officials I've heard them explain away what happened as Britain's intelligence agencies somehow 'losing their way' as they supported the US 'war on terror'.
MI6 was under pressure from a key ally to help track terror suspects who may or may not end up in 'black prisons' being water-boarded or worse or, as in this case, handed over to brutal regimes.
It put the British intelligence state in a very difficult position. Torture and kidnap were then, and still are, illegal - even for the security services.
It's now, perhaps, even more difficult to measure the damage done to the idea of British values because how can this murky episode possibly help British ministers and diplomats when they raise human rights abuses with repressive regimes like China, Iran or Russia.