The United Kingdom has 48 Lockheed Martin [LMT] F-35B fighters under contract for delivery and is looking into the buy of another 26 to bring the U.K. inventory to 74, but the buy will depend upon sustainment cost reductions and the integration of U.K. weapons on the fighter.

Last year, the U.K. conducted an Integrated Review [IR] and a Spending Review [SR] of future programs.

“As part of our planning assumption in the IR and SR that we have just been through, we have assumed an increase of a further 26 F-35B aircraft, which would take the total fleet to 74,” Air Marshal Richard Knighton, the U.K. deputy chief of the defense staff, told the House of Commons Defense Committee on Apr. 26. “We have said that the decision about further purchase, beyond that 74, will be taken in the middle of the decade, in the context of what we decide to do on our Future Combat Air System program. It is perfectly plausible to imagine a situation in which we could have the fleet of 138 F-35s that we originally described back in the early 2000s.”

Knighton said that the U.K. is “in the process of negotiating that additional purchase beyond the 48 with the [F-35] Joint Program Office and with Lockheed Martin.”

“The [U.K.] Secretary of State has been very clear that the final commitment that we make to those aircraft will be dependent on the Joint Program Office and Lockheed Martin demonstrating improvements in cost associated with support and the integration of U.K. weapons,” Knighton said. “But we have set aside the budget for that increase and for the additional infrastructure, support costs and people associated with it.”

Knighton told the House of Commons Defense Committee on Apr. 26 that an integration program has begun on the F-35 for the MBDA Select Precision Effects At Range (SPEAR)-3 standoff air-to-ground munition and the Meteor air-to-air missile.

“The program for integration has started, and we are waiting for definitive dates from the Joint Program Office about when that work will be completed,” he said. “As you can imagine, integrating new weapons on to complex platforms alongside other weapons from other nations is a technically challenging process.”

The U.K. has planned for three F-35B operational squadrons with 12 to 16 F-35Bs in each squadrons. While Britain is to have 12 F-35Bs for routine deployments on either of its aircraft carriers–the HMS Queen Elizabeth or the HMS Prince of Wales–Knighton said that the U.K. may operate up to 24 per carrier and has demonstrated “that we can do that, and the carrier can carry up to 36.”

Britain is likely to rely on U.S. Marine Corps’ F-35Bs to supplement the U.K.’s F-35Bs.

“It is quite clear that in future, when we deploy the carriers, we are going to deploy them with the U.S. Marine Corps,” MP Kevan Jones said at the House of Commons Defense Committee meeting in April. “I have no problem with that. I think it’s just reality. The problem is that we are still stuck in the notion that we are going to have these two carriers with fleets of British aircraft on them when in fact we are not. As I say, I have no problem with it, because I think interoperability with the U.S. Marine Corps is the way forward, but if that means that there is a mixed fleet, the MoD [U.K. Ministry of Defense] and the ministers need to start saying this, because otherwise we are still stuck with the notion that somehow we are going to deploy both carriers together, with full fleets of British aircraft. We are not.”

In May last year, the HMS Queen Elizabeth deployed for the first time in the NATO maritime live exercise Steadfast Defender 2021 (Defense Daily, May 20, 2021). The ship had U.S. Marine Corps and U.K. F-35Bs.