Navy Lookout published a technical read of Mine Hunting Capability (MHC) Block 2 on 11 August and set the requirement in square metres: an offshore support vessel (OSV) with at least 1,000 square metres of working deck, enough to host three or more uncrewed surface vessels, uncrewed underwater vehicles and their control gear1. HMS Stirling Castle, the mothership the Royal Navy already runs, offers roughly 600. That shortfall of at least 400 square metres separates carrying one minehunting system from carrying the three the programme is built around.
The money splits awkwardly. £1.3bn sits inside June's Defence Investment Plan for MHC Block 2 across 2026 to 2030, and the £90m Britain earmarked with Norway in July buys the start of OSV development rather than any steel. Navy Lookout reads that as a minimum initial tranche, written on an assumption that larger sums follow to complete a three-vessel build once estimated at roughly £330m2. Development money buys drawings. A mine countermeasures drone does not deploy without a hull to launch, recover, refuel and command it. The remaining Hunt-class minehunters must leave service by 2032, and HMS Chiddingfold already went in July after 42 years.
The hull requirement itself belongs to a Norwegian programme. Norway's Parliament has approved 28 standardised vessels, 18 coastal and 10 ocean-going, built on an "as civilian as possible, as military as necessary" philosophy, and Britain formally joined under the December 2025 Lunna House Agreement3. Kongsberg's Vanguard Solution family appears in the programme material as an illustration of that philosophy, not as a selected design. Buying into a 28-hull production run costs less per vessel than a bespoke British class, and is correspondingly harder to vary once joined.
The trade runs both ways. Norway chose at least five UK-built Type 26 frigates in 2025, a deal the UK government valued at around £10bn, with DE&S (Defence Equipment and Support) citing strategic offset programmes in the follow-on cooperation, meaning investment a seller nation commits to the buyer's industry as part of a defence sale4. Britain has already proved the difficult part of the concept: the autonomous minehunter RNMB Ariadne docked inside RFA Lyme Bay off Gibraltar at the first attempt on 27 May, the first at-sea recovery of a crewless Royal Navy minehunter into a mothership. Recovery works. Norway's production run is where Britain now intends to buy the deck it happens on.
