Queen setting the bar high for all in Northern Ireland

They killed him, murdered one of his grandsons too and injured other members of his family. The quiet waters round Mullaghmore, County Sligo, turned red.

Some years later I was asked to interview his daughter Patricia Mountbatten. I wrote to her requesting a meeting and warned her that I married my Scottish name; that I am Irish and I sound it.

She lost her son as well as her father in the explosion. Her other son was injured. I wanted to alert her to the fact that my voice might take her back there. In the event she didn't want to be interviewed but, in her reply, she wrote that she loved Ireland and the Irish. She said it had been her privilege to send the bomber's son on a cross- community holiday. It's odd how magnanimity can bring you close to tears.

If I am tempted to be petty, to hold a grudge or be slow to forgive, I remember Patricia Mountbatten. All the justified anger and hot revenge in the world wouldn't add up to a tenth of her tribute to her lost loved ones.

Tomorrow the Queen is to shake hands with Martin McGuinness: the monarch and the reformed IRA commander. The symbolism could hardly be greater, especially for a province which still marks its tribal boundaries with flags and paintings of masked gunmen on gable walls. Who would have thought it could happen? More to the point, should it happen?

Martin McGuinness was active in the IRA when Mountbatten and his grandson were killed. While the Queen has shaken hands with many an African guerrilla leader turned politician, this is up close and personal – and all the more powerful for it.

But the controversy about the greeting has been on the republican side. There are those who still think it is a capitulation; a recognition of partition. So why has the party's ruling body permitted the exchange?

Gerry Adams says it's because he wants to reassure Unionists of their place in his vision of a united Ireland. Others think the Queen outflanked him.

In May last year Sinn Fein boycotted her state visit to Dublin and organised protests against it. Tensions were running high. A bomb threat was received from dissidents and the security bill for the four-day visit was estimated at £26m.

Then the monarch stepped off the plane wearing emerald green and Irish hearts started to melt.

Within 36 hours she had laid a wreath at the memorial for Irish freedom fighters, worn a gown embroidered with shamrocks to a state banquet and opened her speech with the words: "A hUachtarain agus a chairde." (President and friends.)

It was a stroke of genius. When the then Irish president Mary McAleese heard the Queen speak Gaelic she could be seen to say: "Wow."

It was only the beginning. The speech stressed the need for forbearance and conciliation; of being able to bow to the past but not be bound by it.

The Queen said the benefit of historical hindsight allowed us to see things we would wish "had been done differently or not at all".

Ireland loved it and loved her for it. Suddenly populist Sinn Fein was wrong-footed. Its sulking looked small-minded and petty – escpecially when it banned the Sinn Fein Mayor of Cashel from officially greeting the Queen. Michael Browne, who was terminally ill, defied the ban.

The party doesn't plan to make the same mistake this time, a wise decision given that extra tickets have had to be issued for the 22,000-strong Diamond Jubilee party which will be held tomorrow at Stormont. 10,000 free tickets were snatched up in six minutes (four changed hands for £2,500 on an auction site).

So much for Sinn Fein's position. But there will be others who have real difficulty with the Queen's decision to shake hands with Martin McGuinness.

There are bereaved families on both l sides of the Irish conflict, in Northern Ireland and on the British mainland. Does this handshake risk alienating them?

It is the Queen's relationship with Lord Mountbatten that draws that sting.

Mountbatten was her husband's uncle and an old friend. Just before the Diamond Jubilee we saw cine film archives of Prince Charles's childhood.

In one of them Mountbatten arrives aboard Britannia on a bosun's chair strung from another ship. He looks like the Milk Tray man but in full uniform. The next shot shows him taking turns with five-year-old Charles on a water slide. He was one of the Royal Family's inner circle. His loss was keenly felt.

When the Queen reaches out to Mr McGuinness, she will do so as monarch and as head of a state whose forces fought in Northern Ireland. Crucially, she will also do so as a bereaved relative.

It must be hoped that all the others will recognise it as an act of strength, not weakness – for it is far more regal than retribution. The Queen is setting the bar for everyone, and setting it high.

Each representative at the meeting tomorrow has had to shed entrenched views for the greater good. Gathered with the Queen in the Lyceum Theatre for a celebration of culture on the island of Ireland will be Michael D Higgins, the President of Ireland, who has seen his country relinquish its claim to Northern Ireland. There too will be First Minister Peter Robinson. As Dr Ian Paisley's successor, he has moved from the far right of Unionism to power sharing. Martin McGuinness has put his life in danger from dissident republicans to pursue a peaceful future for the province.

None can undo the past. They can't raise the dead or heal the maimed. But they can stop allowing it to dictate the present and threaten the future.

In that same Dublin speech the Queen emphasised the shared values within these islands, the familial, cultural economic and business links that make us firm friends and equal partners.

She said: "Whatever life throws at us, our individual responses will be all the stronger for working together and sharing the load."

It holds good today. It helped inspire that handshake tomorrow. As a native of Northern Ireland and former civil rights marcher, I hope it signposts the future.