The Fountain estate perches uneasily outside old Derry's walls. It is the last Protestant working-class estate on the west side of the River Foyle and, as such, is powerfully emotive to the unionist minority in the city.
Both communities in Derry are wont to point to developments in the Maiden City as a blueprint for what could happen in a united Ireland. This does not mean they share a common view, either of recent history or of the future. Far from it.
Nationalist politicians point to Derry as a model of partnership and inclusivity. This is the city once described as "the capital of discrimination". It was here the first Civil Right marches, beaten off the streets by the RUC, lit the spark for all that has happened since.
Now nationalists are in the majority in Derry City Council. There is power-sharing in the council chamber. The office of mayor is rotated between unionist and nationalist representatives.
Last month, a Sinn Fein councillor, Cathal Crumley (of whom more anon), was elected mayor, the first Sinn Fein representative to hold the office in any city on this island since Terence MacSwiney in Cork.
The thorny issue of marches, which has caused such problems elsewhere, has been resolved in a civilised fashion after negotiations between the Apprentice Boys and the Bogside Residents' Association. The city is booming. Partnership pays is the message.
This is not quite how unionists in Derry see the situation. It is true that, as in the rest of Northern Ireland, middle-class unionists have accepted an accommodation with nationalism. But even they point to the fact there are now only a few hundred Protestants living on the city side.
The rest have been "driven" across the river to the Waterside. There are allegations that they do not get their fair share of the jobs or the funds which seem to flow so freely into nationalist hands.
That is why the Fountain estate and the genuine efforts made to refurbish it are so important. On Tuesday, Princess Anne came to Derry to open a new housing development in the Fountain area. It consists of 28 apartments of sheltered housing for the elderly and a further six for people with physical or mental disabilities. The new development is named after Jack Allen, who represents how far the unionist community has travelled. Born in the Fountain, he is a former UUP mayor of the city who became one of the most loyal supporters of the peace process.
Cathal Crumley was invited, as mayor of Derry, to attend the opening of the new development, named Jack Allen Court. He declined. Various reasons have been given for his decision. The first and most obvious is that, as a Sinn Fein representative, he has no mandate from the people who voted for him to welcome a member of the British royal family to the city.
This was not, Mr Crumley says, intended as a snub. When he became mayor, he promised to represent the interests of both communities. But this was primarily an occasion for unionists and it was better for them "to have their day with their royal visitor". For that reason he asked the UUP deputy mayor, Ernie Hamilton, to represent the city.
Mr Hamilton duly greeted Princess Anne, but expressed regret at Mr Crumley's absence: "As mayor, he should have been here. He would have been welcomed just the same as anyone else." More stringent criticism came from the SDLP's Alban Maginness, a former mayor of the equally divided city of Belfast. He argued that in the present political circumstances Mr Crumley would have shown "greater skill and political courage" if he had officially greeted Princess Anne on behalf of all the people of Derry.
As a fortunate citizen of a republic, I hold no brief for the British monarchy. An increasing number of serious commentators in Britain believe that the institution is unlikely to survive much beyond the reign of the incumbent. That is not the point here. A section of the unionist community in Derry had invited Princess Anne to open a new social housing development. The Sinn Fein mayor was asked, in his official capacity, to represent the city.
There were obvious difficulties for Mr Crumley. As he remarked, there are sensitivities on both sides. But he has been elected to the highest political office in a city which has been bitterly divided in the past and is now trying to work out a way to advance. That is what most people in Derry want. An important part of the mayor's job, whether unionist or nationalist, is to demonstrate there are practical steps which can help to build a better relationship between the two communities.
Sinn Fein talks a lot about "inclusivity", but all too often seems to think this should be a oneway street. It leaders balk at according any courtesy to symbols which are seen as part of "their" tradition. But any leader who is in earnest about promoting reconciliation knows such symbols can be used in a most powerful and non-threatening way.
One has only to think of the Pope praying at the Wailing Wall in Jerusalem, or of Nelson Mandela donning the shirt of the South African rugby team, for so long associated with apartheid.
In Derry this week, a community which feels excluded and under threat had a rare cause for celebration. If he had accepted the invitation to join that celebration, Mr Crumley could have shown that he wants to be a mayor for all the people of the city. It is a pity he turned down the opportunity.