WHETHER the decision to build five new general purpose Type 31e frigates away from the Clyde is controversial depends very much on what you think Scottish shipbuilding was promised.

On the face of it, there isn’t a problem. UK defence minister Michael Fallon says the fact that the whole contract for eight type 26 anti-submarine frigates will be Clyde-based means 20 years of guaranteed work.

He is offended by talk of betrayal: The SNP is guilty of “turning sunshine into a grievance” he has said. BAE systems itself says existing work will keep its the Clyde order book full until the mid 2030s.

But that relates to existing capacity. The original plan was for 13 type 26s to be built, with the MoD downgrading that to eight, with five of the cut price Type 31 warships ordered instead. These lower spec, lower priced frigates – yet to be designed – are to be brought in at under £250 million each. At that price, the MoD hopes it may also secure international exports.

The original plan might have seen expansion on the Clyde. The workforce was hoping so, after restructuring and job losses aimed at equipping BAE for the future. There was talk of a ‘frigate factory’ on the Clyde, but the lower price and simplicity of the new warships means investment in the necessary expansion is impractical – perhaps one reason why BAE declare themselves satisfied with this new agreement.

But the SNP and local MPs are convinced Scotland was promised more, and this is argument is lent additional heat by the claim that reassurances were given ahead of the Independence referendum to help encourage No voters.

A further dimension is the need for three support vessels which will be needed to back up both sets of frigates. These much bigger vessels represent a lot of potential ship-building work. UK firms argue such work could be carried out in Britain on the same model as the recent aircraft carrier-building programme – with construction carried out in separate yards before elements are brought together and assembled in one location. In the case of the two QE aircraft carriers, assembly was carried out at Rosyth.

This is the approach recommended by Sir John Parker in his 2016 shipbuilding review. But the UK government is committed to opening up the tender exercise for the support vessels to international competition – leaving observers fearing the work could end up in South Korea.

This announcement of a partnership between BAE Systems and Cammell Laird is only an agreement to bid together, so the outcome is not guaranteed. Should they not win the contract to build the Type 31 ships, unions say this will further undermine the Clyde yards role as the one place that can design, engineer, build and deliver complex naval ships from end to end.

Shipbuilding may be guaranteed until the 2030s, but design work onthe Type 26 warships is already well underway. If BAE Systems does not secure the design element of the contract for the newer, cheaper frigates, it may be hard to retain those skills in the future.