The SSN-AUKUS Preliminary Design Review was conducted in June and concluded on 1 July, three months earlier than the September date it had been expected to meet, according to an answer given in Parliament.
Ben Obese-Jecty, the Conservative member for Huntingdon, asked for what reason the scheduled September 2026 Preliminary Design Review date for SSN-AUKUS was missed and what the new date was.
Luke Pollard, the Minister of State for Defence, said: “The SSN-AUKUS Preliminary Design Review was conducted in June 2026 and concluded on 1 July as part of the ongoing Detailed Design and Long Lead (D2L2) phase of the programme.”
A Preliminary Design Review on a submarine programme locks the overall configuration before detailed design work proceeds at scale, covering the hull form, the compartment arrangement, the propulsion and combat system integration and the weight and stability margins. Passing it allows long lead items to be ordered against a stable design, which matters on a programme where reactor components and large forgings have ordering lead times measured in years.
SSN-AUKUS is the replacement for the Astute class and the design Australia will also build, developed by BAE Systems at Barrow with Rolls-Royce providing the reactor plant and a trilateral arrangement governing the common elements. The boat is larger than Astute, carries vertical launch capacity and is intended to accommodate uncrewed systems alongside torpedoes and cruise missiles.
Detailed Design and Long Lead runs to 2028, and the programme is midway through it, with Pollard confirming in a separate answer the same day that the number of boats will be settled before the phase closes. Steel will be cut on the first British hull next year, a milestone this publication has covered as it approached.
Design reviews slipping to the right has been the pattern across large defence programmes for a generation, which is what prompted the question. Submarine design on this programme has run with a deliberately conservative schedule built around the Barrow drumbeat, and Dreadnought holds the priority on the same design and build resources.
Australia’s Osborne yard in South Australia will build to the same design, and the Australian Submarine Agency has its own review gates aligned to the British ones, so an early conclusion on the British side gives both partners margin before detailed design work peaks. Rolls-Royce in Derby is producing reactors for both classes from a doubled site.
Obese-Jecty’s question assumed a missed milestone and received a date that had already passed. The review closed on the first of July and the programme has been running on from it since.












“conservative build rate” In other words, as slowly as possible to keep the Treasury happy.
Oh ye of little faith, which TBH is perfectly understandable given decades of lies, damned lies and statistics. 🥴
However the physical and monetary evidence is there in front of you, if you know where to look and how to interpret it. Old saying is money talks and in this case it’s just mind boggling the sums being invested by 2 separate but Treaty obligated Nations.
Barrow, Derby and SFM are all being ripped apart, modernised, rebuilt and expanded and as I live here in Derby I can tell you that the extra parts of the site (and some of the existing one) was being acquired, cleared, levelled, piled and Transport connected 2 years before AUKUS was even announced. Life was conveniently made easier when HMG did a sleight of hand trick and used land it owns to the west of the site to build a High security multi story car park for the enlarged RR workforce before the enlargement was even announced ! They just need Network Rail to put in a footbridge bridge over the Midland Mainline as the present arrangements aren’t very good (30 minute walk or use the shuttle bus).
It’s all now in the public domain that there are 7 PWR reactors in the RR build process and only 4 of them needed for the Dreadnoughts so guess
what ? AUKUS SSN/A isn’t just a project it’s already in build in the supply chain and it’s on a fast drumbeat.
As for the bit about the build rate well yes I am the first to point out that the Sclerotic delivery schedule of the Astutes was down 100% to HMT. Not only was the scheduled delivery down to them but the delays caused by the entire Submarine delivery industry having been run into the ground before we even started.
Happily this isn’t the case this time, the Money is there, being spent ahead of schedule, long items are in build and the big stick is now to deliver what we have for ourselves and Australia on cost and in time so we just have zero option but to build at an optimum production rate.
Slow build = increased costs and I doubt Australia will be slow at Sledging us Pomms if we try to pass on a price increase because we have mucked it up.
The treasury might well be keen to move the project along. More money is predicted and the treasury will be keep to get the various projects mopping up the cash at an even rate. Demonstration of higher spend ASAP is important to our leadership role in NATO.
Hopefully this means things are turning a corner with SSN production.
Moving the boats along to a quicker drumbeat is probably best for everyone. Also a larger number of boats indicates a lower price per unit.