Fifteen years on and the sight of Northern Irish politicians walking up to the door of 10 Downing Street – once a staple for television bulletins – has become a rarity.

During Tony Blair's years, they had near-open access. Under his successor, Gordon Brown, it was restricted to times when Brown believed it necessary, while under David Cameron the number of examples has fallen, almost to nothing.

The image reveals much of the changed order. For many in London, NI politicians of all hues had become addicted to the profile where “peace processing” had, in their eyes, become an end in itself.

Following Cameron's arrival in No 10 in May 2010, he was determined that much of the old order would resume, with the Northern Ireland Office becoming, once again, the designated point of contact. His view was simple, if not a little simplistic given Northern Ireland's history: the North had its Assembly and Executive and it was up to the local institutions to govern, he believed.

The change has not gone down well. Northern Irish politicians bridled at being limited to Owen Paterson, a shire Tory of the old guard, and his successor in the Northern Ireland Office, Theresa Villiers.

Corporation tax
Paterson, unlike some of his predecessors, used up shoe-leather during his time as the Conservatives' NI shadow secretary in opposition, even if Martin McGuinness believes he "came in like a lion, and left as a lamb".

So far, however, Villiers, has not impressed local politicians, even though it is clear that Cameron has given her the same gate-guarding role once held by Paterson: to keep Northern Ireland away from No 10.

The North’s visibility has fallen on all fronts: the establishment of functioning, or at least lasting, institutions in Stormont has meant that it has ceased to be an issue on the floor of the House of Commons.

First Minister Peter Robinson and Deputy First Minister Martin McGuinness were invited to Downing Street last month for a meeting on corporation tax – a long-standing point of agreement between two men who often agree on little else.

However, the meeting occurred because of Cameron’s concerns that the issue had to be parked this side of the September 2014 Scottish referendum, rather than because of a determination to resolve it.

Judging by the clear anger of Robinson and McGuinness outside Downing Street later, it was clear that both had had no illusions about the nature of the meeting, or, indeed, the dangers that the prize could be slipping away.

If Scots vote to stay in the union, then Robinson and McGuinness will renew the push for tax flexibility in the gap between the referendum and the election due in May 2015, though few believe that enough time will be available.

Equally, Cameron’s and Villiers’s lack of visibility during last December’s flag protests in Belfast would have been unimaginable had such violence occurred not in Belfast, but in a British city.

They would argue that local political institutions had to be faced with the primary responsibility for handling a local crisis, if the institutions are ever to develop the resilience necessary for long-term survival.

However, the danger, or perhaps, more accurately, the fear, is that worse challenges will have to be faced in time by an unprepared Downing Street.

Then, relationships and ties needed on such a day may not be there to be found.

Such ties had to be built once before from the early 1980s onwards – over drinks late at night at meetings of the British-Irish Association and a host of other venues – when work that led to the Anglo-Irish Agreement began.

In November 2010, a group of ageing men, many of them now frail and some who have since passed on, clambered up the steps of the Irish Embassy in London to renew those bonds forged 25 years before.

Hard-won bonds
The group included former taoiseach

Garret FitzGerald, Lord Geoffrey Howe, former Northern Ireland secretary of state, Lord Tom King and a slew of civil servants, some now leaning on walking-sticks. Such bonds were hard won.

Today, that institutional memory in Dublin and London, but particularly the latter – that was freshened subsequently by all those involved in the Belfast Agreement negotiations – is beginning to fade.