"Where did it all go wrong?" would have been a natural question for the Queen to ask her ministers Peter Robinson and Martin McGuinness last night when she gave them individual audiences at Hillsborough Castle.
The only written records of an audience with the monarch are a brief note in the court circular.
The idea is that people can, within the bounds of protocol, speak frankly during their one-to-one face time with the sovereign.
It is understood that her questions can also be frank, even probing. Her first meeting with Mr McGuinness was on June 27, 2012 in the Lyric Theatre.
Despite the groundbreaking nature of the event and the feelgood factor which it generated, things have not gone that well in Northern Ireland.
She may recall Peter Robinson assuring her that "an age-old quarrel has been set aside and politics is working". It doesn't look like that today.
The Haass talks have crashed and burned, and hopes of a revival are fading as the marching season and then a string of elections hove into sight. Speaking of the marching season, both ministers are avoiding important trade missions because of the real danger that trouble may erupt.
The risk of being filmed in Rio enjoying corporate hospitality if the streets around Ardoyne were exploding would be so great that they have turned down an invitation from Marfrig, the Brazilian agri-food giant that is our biggest industrial employer.
The terrorist threat persists at a low level. Yet the dissidents must be encouraged by the knowledge that trust levels are falling at Stormont and decision-making is mired in suspicion and mistrust.
Failure to agree welfare reform is an increasing, and unsustainable, drain on public finances and blocking tactics are the order of the day.
In another sense, the Queen and Martin McGuinness may look back on how difficult that first meeting between them had been to arrange and choreograph and how much things have moved on since. Now meetings seem almost routine and we have dispensed with the fig leaf – employed by Mr McGuinness the last time she was here – that he wasn't meeting her in an official capacity.
There was a lot of flim-flam to get it all through the Sinn Fein ard chomhairle, which had, a year earlier, opposed a royal visit to the Republic. The meeting wasn't on the Queen's home turf and wasn't even, it was said without much conviction, part of her visit to Belfast. It was a charity event in a theatre which they both happened to be attending alongside Michael D Higgins, the Irish President.
Now that has all been dispensed with. Mr McGuinness is, just like Peter Robinson and Theresa Villiers, the Secretary of State, enjoying an audience with the Queen at her official royal residence in Northern Ireland.
Getting this far must have taken considerable courage on both their parts.
Her Majesty may have remembered her kinsman Lord Mountbatten who was killed in an IRA bombing together with three other people. That was in 1979, a time when most historians record that Martin McGuinness was IRA chief of staff.
Mr McGuinness may remember the Bloody Sunday shootings of unarmed civilians by the British Army. "The men responsible were marched up to Buckingham Palace and they were decorated by the British Queen. How do people think we feel about that?" he asked angrily after the 1994 IRA ceasefire allowed Sinn Fein to deal openly with the British Government. However, after a big effort by the two of them, meetings are now routine. That should have had an unfreezing effect on politics here. Mr McGuinness said, at the time, that he wanted to symbolically shake the hands of every unionist along with the Queen, and he obviously hoped for easier relations in Government as a result. Besides the Mountbatten atrocity, Her Majesty escaped at least two IRA attempts on her life, one at Sullom Voe in the Shetlands and the second at Coleraine during a previous visit.
She must have hoped that by showing an example she would help to stabilise this part of her realm. She may even have calculated that her personal effort would encourage those most loyal to her to work alongside others for the common good.
Instead, the biggest result of her diplomacy has been better relations between Britain and the republic. Northern Ireland remains a difficult problem.