Perhaps it was the weight of evidence in his favour. Perhaps it was clear to even Whitehall mandarins & ministers that the Bulgarian judicial system's rudimentary approach to criminal matters was a sick joke, thus rendering realpolitik just this once irrelevant. Perhaps the excellent & sterling campaign waged by his family persuaded countless others to take up the case in a way which couldn't be ignored. Perhaps Justice Secretary Jack Straw, defending what is sure to be a Labour marginal at the next election, was spooked at the thought of his father standing against him.
In all probability, all the above factors have played their part in securing justice for Michael Shields today (http://news.bbc.co.uk/go/click/rss/1.0/-/1/hi/england/merseyside/8245760.stm ).
Today is clearly a day for celebration among Michael's family & friends. They won't want to dwell too much on the wider issue of this being a gross miscarriage of justice, perpetrated while a Labour government largely kept schtum because of Bulgaria's application for EU membership.
Not today anyway.
Nor will they be thinking too much of the identity of the individual responsible for the attack who has effectively got away with it while Michael was wrongly convicted.
Everyone on Merseyside knows the identity of the low-life whose cowardly attack & subsequent actions caused so much misery & distress for Michael's family.
If the notoriously slow wheeels of the judicial system do not turn sufficiently quickly in delivering final justice for not just Michael, but Martin Georgiev, the Bulgarian victim of the attack, this blog will name him as a matter of course.