Visit to heal the violent separation of Britain and Ireland

The Irish President's State Visit puts a full stop on the healing story of the British and Irish States since their painful and violent separation nearly a century ago. In truth the last few sentences of that story have been about what good friends they are now; from The Downing Street Declaration to the Queen's remarkable visit to Dublin in 2011.

Read: Irish President to meet the Queen in historic state visit

But the story which concludes in Windsor today is only one, and it's neat ending serves only to highlight those which have not ended so cleanly. Northern Ireland is full of messy, unfinished business. There are some 3000 unsolved murders, thousands of relatives across the UK who are desperate for truth and justice.

It is beginning to look like they may not get both.

This week the former Northern Ireland Secretary Peter Hain said it was time to stop pursuing prosecutions for old crimes for which there is little remaining evidence. He argues that lifting the threat of prosecution would make it more likely that those who know what went on in the conflict there would come forward.

Read: Calls for an end to Troubles-era prosecutions

Some families are willing to sacrifice justice for truth, but not all of them trust the perpetrators to keep their side of any bargain.

More: Enniskillen survivor finds proposal to end prosecutions 'totally disgusting'

For them the presence of Martin McGuinness at the State Banquet in Windsor tonight is less a symbol of how far Britain and Ireland have come, and more a reminder of how little he and those like him have revealed about what they did during the long dark days of 'The Troubles'.