Boeing said that under the terms of its takeover of Spirit, the supplier is proposing to sell non-Airbus activities in Belfast to a third party. Sources said that represents a declaration of intent and that there’s no prospect of a quick sale.

Airbus confirmed that it will take on operations including wing production in Belfast and other A220-related work in the US and Morocco, as well as manufacturing of fuselage sections for the A350 wide-body plane in the US and France.

Airbus will pay Spirit a nominal $1 while receiving $559m in compensation for assuming responsibility for the unprofitable activities.

Should a buyer not be found for a subsidiary business in Prestwick, Scotland, which makes wing slats for the A320 jet, Airbus said it would also be prepared to take that on as it works through a record order backlog for the popular single-aisle plane.

However, there is no such safety net in place for remaining operations in Northern Ireland.

Sir Michael Ryan, chairman of Spirit UK, warned in April that a break-up of the Belfast business would be “extremely detrimental” to its future and to the province’s wider standing in the aerospace industry.

In a letter, he said that maintaining the site as a single entity was the best option, and that vital economies of scale and technological synergies could otherwise be lost.

Spirit’s Belfast footprint spans six sites, including some located in the Catholic west of the city regarded as integral to the Northern Ireland peace process.

The main factory, sandwiched between Belfast City Airport and the docks, was built by Short Brothers in 1936 and produced Second World War aircraft including the Stirling bomber and Sunderland flying boat.

Shorts began trading in 1897, making hot-air balloons before switching to aircraft after the Wright Brothers’ first flight.

The company built six planes on the Isle of Sheppey in 1909, making it the first in the world to undertake volume aircraft production.

It was sold to Canada’s Bombardier in 1989 and to Spirit in 2020.