The U.K. defense ministry is making the final preparations for purchasing its first squadron of F-35 Joint Strike Fighters.

After the £74 million ($114 million) government flip-flop, changing to the F-35C conventional carrier-borne version in 2010 and then reverting to the short-takeoff-and-vertical-landing variant F-35B in 2012, officials are looking toward “Main Gate 4,” a procurement contract milestone that will not only buy the U.K.'s first squadron but also begin the transition toward operations. It is understood the order will be for around 14 F-35Bs.

Speaking at the Professional Engineering Institution's (PEI) annual defense lecture in July, Royal Navy Commo. Rick Thompson, the head of the Lightning II project team in the U.K.'s Defense Equipment & Support organization, said the first squadron of British aircraft should move back to the U.K. in 2018. At that time, they would begin trials with the first Queen Elizabeth-class aircraft carrier with the aim of achieving an initial land-based operating capability in late 2018.

When the U.K. entered the program, it announced it would buy as many as 138 aircraft, although the commitment so far is for 48. A Main Gate 5 decision—due around 2017—is expected to approve the remaining balance of the first tranche of F-35 procurement. Thompson says no decisions would be taken before the next Strategic Defense and Security Review in 2015, in which officials are expected to firm up the final number of JSFs the U.K. will buy. He would not comment on whether the U.K. would purchase more than 48.

Despite JSF being envisioned for carrier-strike operations, the Royal Air Force (RAF) seems to be taking an increasingly leading role. A key RAF station at Marham in Norfolk has been selected as the main operating base for the aircraft, and two RAF squadrons will lead the type into operation. The 17 Sqdn. is scheduled to be re-formed under the banner of a Lightning Operational Evaluation Unit in 2015 at Edwards AFB, Calif., while the noted 617 Sqdn., the Dambusters, will become the first operational squadron. Both squadrons will be jointly manned by Royal Navy and RAF personnel. Only the second operational F-35 unit is slated to carry a Royal Navy squadron designation.

So far the U.K. has taken delivery of three F-35Bs, all of which are now operating with the joint U.K./U.S. Marine Corps training unit at Eglin AFB, Fla. Two pilots—one Royal Navy, the other RAF—are being trained as instructors on the type. Approximately 20 maintainers have also been trained at Eglin. Even though the aircraft are operated under the U.K. military register, the U.K. jets routinely switch between being flown by U.S. Marine Corps or RAF pilots via a special regulatory arrangement between the U.S. Defense Department and the U.K. Ministry of Defense.

The British aircraft will eventually move to Edwards AFB in 2014 to begin operational test and evaluation. British personnel are in place at Edwards to begin preparatory work for the arrival of the aircraft. In the third quarter of 2014, pilots will begin being trained at the Marines Corps center in Beaufort, S.C., which is being updated to handle the trainees.

Among the weapons to be integrated first will be Raytheon's Paveway IV and the MBDA AIM-132 Asraam air-to-air missile for external carriage. Officials hope to integrate the MBDA Meteor into Block 4 and are studying options to expand the type's air-to-ground capability through the U.K.'s Selected Precision Effects at Range (Spear) program. Officials close to the Spear program say the Lightning II could carry up to 24 Spear III missiles—regarded as replacements for the Dual-Mode Brimstone weapon currently employed on the Panavia Tornado GR4—while Raytheon is working on a series of capability improvements for Paveway IV, in readiness for the JSF.

Thompson says work on the Block 4 is underway, and that such upgrades would take six years to develop because of the time taken to define the requirements. Officials have pointed out that JSF offers an opportunity for “increased international collaboration” in the event of coalition operations with nations having the potential to use each other's weapons in the event of an urgent operational requirement.

A critical part of the program for the U.K. will be in supporting the aircraft. Thompson says it is the U.K.'s aim to deliver the same level of support capability, whether the aircraft is on “land or sea,” via Lockheed Martin's networked Autonomic Logistics Global Support Solution

“Achieving the same level of support at sea as on land is essential,” Thompson emphasizes, and the processes to achieve this were clearly demonstrated when operating the Joint Force Harrier (JFH) construct, which saw the joint operation of the Harrier GR9 by Royal Navy and RAF squadrons embarked in the Invincible-class carriers. The Lightning II carrier strike operation is likely to emulate much of the JFH structure with one main difference—the ship has been designed from the ground-up to accommodate Lightning II.