RAF’s final F-35B arrives as Defence Investment Plan delay freezes any new Lightning order
April 4, 2026
The UK’s military procurement body, Defence Equipment & Support (DE&S), announced on 27 March that it has accepted delivery of its 48th short take-off and vertical landing (STOVL)-configured F-35B Lightning II fifth-generation multi-role fighter from Lockheed Martin.
This latest delivery marks a key milestone for the UK Lightning Force (UKLF), which has now received all of its first batch of F-35Bs.
The arrival of this final Tranche 1 jet grows the UK’s current inventory of F-35Bs to 47 aircraft. One airframe (serial ZM152/‘018’) was written off after it plunged into the Mediterranean Sea while attempting to take off from the Royal Navy’s flagship aircraft carrier, HMS Queen Elizabeth (R08), during the warship’s maiden international deployment in November 2021.
This latest handover follows a string of recent deliveries that have seen the UK’s newest F-35Bs handed over complete with the jet’s long-delayed Technology Refresh 3 (TR-3) update package – a major hardware/software upgrade that will serve as a key enabler for the fifth-generation fighter’s highly anticipated Block 4 capability enhancements.
While the aircraft have been delivered equipped with the TR-3 update, the upgrade package has yet to be approved for combat use.
Under the UKLF, the British F-35B fleet is operated as a joint force by the Royal Air Force (RAF) and Royal Navy Fleet Air Arm (FAA) in a similar manner to how the UK’s former Joint Force Harrier fleet was employed before it was controversially withdrawn from use in December 2010.
The UKLF is headquartered at RAF Marham in Norfolk and is composed of three different operational squadrons. Its frontline units comprise the RAF’s famed No 617 Squadron ‘The Dambusters’ and FAA’s 809 Naval Air Squadron ‘Immortals’, while the former’s No 207 Squadron serves as the fleet’s Operational Conversion Unit (OCU).
While crews are assigned to specific frontline units, the British F-35B fleet is pooled as a mixed fighting force, meaning that no one squadron has dedicated aircraft assigned to it.
What are the next steps in the UK’s F-35B procurement plan?
While the UK has now welcomed its 48th and final F-35B of its initial Tranche 1 procurement batch, London is expected to place a follow-on order for more examples of the fifth-generation fighter in the near future.
The UK – which remains to be Washington’s sole Tier 1 partner in the US-led Joint Strike Fighter (JSF) programme – still maintains a programme of record that calls for the eventual procurement of 138 F-35Bs.
The nation’s F-35B procurement plans have become something of a political flashpoint in recent years, with many speculating that the UK will cut its total Lightning II order.
However, as per current plans, the UK remains committed to acquiring 138 aircraft, although it now seems that they may not all be examples of the STOVL-capable F-35B, but a mixed fleet that includes the conventional take-off and landing (CTOL)-configured F-35A.
Published by the UK Ministry of Defence (MOD) in June 2025, the Strategic Defence Review (SDR) announced its plan to acquire 12 F-35As for RAF use.
The procurement of these jets comes as the UK moves to reestablish the RAF’s ability to deliver airborne nuclear weapons under NATO’s nuclear-sharing deterrence initiative – a capability that Britain lost when it fully transitioned to a solely submarine-based nuclear deterrent in the late 1990s.
Details regarding the UK’s purchase of a second tranche of F-35Bs are expected to be formally confirmed in the MOD’s long-delayed Defence Investment Plan (DIP), for which a publication date has yet to be announced. The DIP will outline London’s defence spending plans for the next decade.
As per current plans, the UK is expected to purchase 27 Lightning IIs as part of its second procurement batch before the end of this decade. While this was initially thought to solely comprise the STOVL-configured F-35B, the recently announced plan to acquire 12 F-35As for the nuclear role may see this evolve into a split purchase, with 15 F-35Bs and 12 F-35As being procured in total.
RAF F-35Bs: Defending allies in the Middle East
In recent weeks, eight British F-35Bs and crews from No 617 Squadron have been deployed to RAF Akrotiri in Cyprus – alongside a number of Typhoon FGR4s – to perform air defence operations over the Eastern Mediterranean and Middle East regions.
From Akrotiri, the jets have been employed to counter swarms of Iranian one-way attack drones and ballistic/cruise missiles that have been launched against its neighbours in the Gulf amid the US and Israel’s ongoing offensive with Tehran.
These aircraft and their crews have been involved in flying defensive missions across the region since late-February. Such activities have seen crews from the UKLF successfully score their first air-to-air engagements against Iranian one-way attack drones.
Together with the deployed Typhoon FGR4s and FAA-operated Wildcat HMA2s, the F-35Bs and their crews have now exceeded 1,200 flight hours during defensive operations across the region since the conflict began.
Featured Image: An F-35B from the UK Lightning Force enters the hover during a demonstration performed at RAF Fairford, Gloucestershire, during the Royal International Air Tattoo 2025. Photo: Khalem Chapman
