Image source, Reuters

Northern Ireland assembly members and and MPs have joined the crowd blocking the Garvaghy Road.

Deirdre Hargey, Carál Ní Chuilín and Paul Maskey from Sinn Féin and Justin McNulty from the SDLP (Social Democratic and Labour Party) are there and have linked arms with protesters.

Darran Marshall
BBC News NI

Just before 08:00, 30 Orangemen gathered outside Drumcree Church.

A police bronze commander then radioed his team and asked if the route was clear for them.

After a few minutes, he informed the Orangemen that the road was not clear.

They have returned to their hall, to avoid the rain, as they await a police determination that the road is clear.

Darran Marshall
BBC News NI

Orangemen have begun lining up at Drumcree Church ahead of a planned parade in a few minutes for the mile-long walk, which takes in the Garvaghy Road and ends at the Orange Hall at Carleton Street.

The Parades Commission, which decided the march could go ahead, put restrictions on the event, saying no more than 35 people and no bands were allowed to take part.

The Garvaghy Road is currently blocked by protesters.

Mark Simpson
Communities correspondent in Portadown

The focus of decision-making has been passed from the Parades Commission to the High Court to the police.

Senior officers will have to determine whether the march can go ahead or not, for security reasons.

As things stand, there is no clear path down the Garvaghy Road as protesters are blocking it.

The march is due to begin very soon - just before 8am - from Drumcree Church.

Decision time is approaching for the police.

Enda McClafferty
BBC News NI political editor

Northern Ireland Secretary of State Sir Chris Bryant is coming under pressure from Sinn Féin to ban the Orange Order parade along the Garvaghy Road.

It’s understood First Minister Michelle O’Neill has asked him to intervene after the courts rejected a bid by residents to stop the march in the early hours of this morning.

The secretary of state has the power to act against the parade if police have concerns about serious public disorder.

Under public procession legislation, the secretary of state can revoke a decision by the Parades Commission - the body that rules on marches and parades in Northern Ireland - but only if he is asked to review the decision by Northern Ireland's chief constable.

This could happen if police are concerned about serious public disorder.

There has been no official response from the secretary of state or Northern Ireland Office.But it’s understood as yet the PSNI has not asked the secretary of state to review the determination.

Image source, Brian Lawless/PA Wire

The first and deputy first ministers of Northern Ireland have both appealed for calm ahead of this morning's Orange Order parade.

First Minister Michelle O'Neill, from nationalist party Sinn Féin, and Deputy First Minister Emma Little-Pengelly, from unionist party the Democratic Unionist Party (DUP), have different views on whether the march should go ahead - O'Neill opposes it, while Little-Pengelly supports it.

O'Neill, speaking on X, said Garvaghy Road residents were "completely horrified" and that she supported the "protest against this unwanted sectarian march".

However she also said she was "calling for calm on all sides".

Little-Pengally, in a social media statement, said she wanted to "appeal for calm and leadership" and said there is "no violence or threat from the Orange Order".

The Police Service of Northern Ireland (PSNI) are warning people gathering on the Garvaghy Road that their protest is illegal, as Ireland correspondent Chris Page reports above.

There's a large group of people on the road in Portadown this morning, ahead of the planned parade.

Some are carrying banners and posters. There's a large police presence.

Chris Page
Ireland correspondent in Portadown

Image source, Reuters

This is the most contentious parade in Northern Ireland.

Nationalist residents who live along the Garvaghy Road say any parade is unacceptable, the Orange Order say they are righting a wrong.

A large crowd blocked the road overnight, hundreds have gathered and they say they're determined to stop the parade.

There is a police presence and the crowd has been told over a loudspeaker that no notice of the protest was given and that people taking part in a protest is committing an offence and could be arrested.

Darran Marshall
BBC News NI

Hundreds of people have gathered at the junction of the Garvaghy Road and Drumcree, on the outskirts of Portadown.

They’ve linked arms and are singing songs.

As a large media contingent keeps tabs, police are announcing over speakers that demonstrators must disperse.

A second group of protesters have congregated a few hundred metres further down the road.

For a few years in the 1990s, the Drumcree parade dispute in Portadown was one of the biggest stories in Northern Ireland.

Orange Order members took part in the parade - the Order is a Protestant organisation which takes part in thousands of parades across Northern Ireland every year.

The biggest day of the marching season is 12 July when they commemorate William of Orange's victory over the Catholic King James II at the Battle of the Boyne in 1690.

However, many Catholics see the marches as sectarian and, in the 1990s, there were disputes over those that passed through, or close to, Catholic or nationalist areas.

The Garvaghy Road had been part of the Drumcree route, but by the mid 1990s nationalist residents protested against the parade.

When the Orange Order was prevented by police from walking down the route in July 1995 there was a tense stand-off. It was the same for the next three years.

Violence related to the dispute resulted in riots, roadblocks and murders across Northern Ireland.

In 1998 the newly-established Parades Commission ruled that the Orange Order should not march down the road and that has been its position up until Friday.

Read more here.

Image source, Getty Images

We'll come to the historical background to the marching dispute over the Orange Order's march out to Drumcree church but - first - let's bring you up to speed on 48 hours of rulings that had this morning's parade on, then off and then on again.

Friday: The Parades Commission - the body in Northern Ireland that decides on whether marches should go ahead and if any restrictions should be applied - rules that the Orange Order should be allowed to proceed down the Garvaghy Road for the first time since 1997.

Many residents on the road, a mainly nationalist area, have long objected against the order, the largest Protestant organisation in Northern Ireland, from proceeding down the road.

This judgement departed from almost three decades of decision-making by the Parades Commission to not allow parades down this route.

Saturday: An initial legal challenge from the Garvaghy Road Residents' Coalition (GRRC) at the High Court saw a judge issue an injunction banning the parade on Saturday afternoon.

However, this was challenged by an Orange Order member with the Court of Appeal sitting at 9.30pm. It ruled, shortly before midnight, that the judge had "erred in law" in placing the injunction.

This led to a fresh High Court hearing, which began in the early hours of Sunday, and a ruling at 2.15am that the initial Parades Commission determination must be respected.

Now, on Sunday, we're expecting 35 members of the Orange Order to begin their march in just under an hour.

Later this morning, at about 8am, members of the Orange Order are due to set off for a march that will take them down the mainly nationalist Garvaghy Road in Portadown, County Armagh.

The route of this parade, the source of a dispute which in the 1990s sparked some of the most serious disorder in Northern Ireland's history, has been steeped in contention for decades.

Now, it's set to happen after 24 hours of legal drama in Belfast that saw the High Court rule in the early hours of Sunday morning that an initial decision to let the march go ahead must be respected.

We'll have all the latest this morning as the march sets out, so stay with us.