Windsor Framework: How will the next stage of the Brexit deal work?

The implementation of the Windsor Framework has reached a major milestone on Sunday as the green lane/red lane system starts operating, but how will it work?

Let's start by explaining what the Windsor Framework is.

It is the post-Brexit trade deal for Northern Ireland, amending the original deal known as the Northern Ireland Protocol.

The protocol and the framework have the same basis: they keep Northern Ireland inside the EU's single market for goods.

This means that goods can flow unimpeded between Northern Ireland and the Republic of Ireland.

However goods coming from Great Britain into Northern Ireland face a range of controls and checks.

The aim of the framework is to reduce the level of controls on goods coming from Great Britain which are intended to be sold in Northern Ireland.

The first thing to understand is that you will not see green and red lanes at NI ports - it is more of a concept than a physical reality.

The basic idea is that goods which are moving through Northern Ireland into the Republic of Ireland and the wider EU will have to use red lane procedures.

That means full customs documentation and checks at the ports for some products.

Goods which are coming from GB to be sold to consumers in Northern Ireland will use the green lane, meaning minimal paperwork and few routine checks

Companies will have to be signed up to a new trusted trader scheme to use the green lane.

Under the protocol all food products entering NI needed to meet EU standards.

But under the framework food being sold to consumers can be produced to UK standards.

This will formally end the "sausage war" - a ban on chilled meat products from Great Britain being sold in Northern Ireland.

A one stage, this was a source of significant dispute between the UK and EU even though the ban was never implemented due to grace periods.

The flipside of this change is that some food products arriving from Great Britain will need to be labelled as "not for EU".

This has already been happening ahead of Sunday's launch date.

Posters with a "not for EU" message will also have to be put up in shops.

This is all to reassure the EU that products which do not meet its standards are not being sold in the single market.

But there will be no prohibitions on shoppers from the Republic of Ireland taking goods home from Northern Ireland supermarkets.

The horticulture industry has felt significant effects from the protocol.

There were new requirements for inspection and certification of plants being moved from Great Britain to Northern Ireland.

Some products, such as seed potatoes have been entirely banned.

Now instead of full EU certification plants and seeds will move under a new simplified Northern Ireland Plant Health Label Scheme.

The GB seed potato ban will also be partially revoked: trade between registered operators will be possible but not sales direct to consumers.

Business organisations have complained there was a long gap between the deal being agreed and operational guidance being provided.

Earlier this month supermarkets warned of potential difficulties with moving some "rest of the world" goods to NI via GB.

That issue is now understood to have been resolved with a temporary fix while the government works on long term guidance.

The phrase being heard in the retail industry is "working towards compliance".

That means that, for example, businesses won't be expected to be 100% compliant with labelling on day one but will have to show that they are working on getting there over the next few months.

Politically it is not in the interests of the UK and EU to come down hard on businesses as they are trying to implement the new processes.

Some businesses are likely to face ongoing bureaucracy, particularly food wholesalers who distribute goods across NI and the Republic.

They may have to move much of their product via the red lane.

The framework deal represented a significant improvement in relations between the UK and EU.

In its aftermath they signed a memorandum of understanding for cooperation on financial services regulation and later agreed terms for the UK to rejoin the EU's research funding program, known as Horizon Europe.

Northern Ireland's nationalist parties and the centrist Alliance Party support the framework as a necessary compromise for dealing with the fallout from Brexit.

Unionist parties oppose the framework, saying it is not sufficiently different from the protocol and continues to undermine NI's place in the UK.

The largest unionist party, the Democratic Unionist Party, is continuing to boycott devolved government in Northern Ireland in protest at the framework.

The government has said it will legislate to strengthen the guarantee that NI goods can be freely sold to GB but will not reopen negotiations with the EU.

The DUP's Sammy Wilson told the BBC's Good Morning Ulster programme that the Windsor Framework "weakened" Northern Ireland's place within the UK.

"The evidence is there," he said.

"There will be different laws applied to Northern Ireland without any democratic control."

The SDLP's Claire Hanna said the framework "is the available compromise after years of torturous wrangling over how we reconcile our geography, our economy and the Brexit that Britain chose.

"The framework is what we have, it is coming whether people like it or not."

Alliance Party assembly member Sorcha Eastwood said the framework provided "an opportunity for Northern Ireland in terms of having dual market access".

There are further parts of the framework to be implemented over the next two years.

These include the expansion of 'Not for EU' labels to the rest of the UK in 2024.