The UK didn't formally join the program until 2001? I don't know how much money was involved, but there was certainly deep involvement.
Ambassador Kerr: Three words from the United Kingdom Government -- priority, confidence, partnership.
Collaboration on JSF is a very high priority for the United Kingdom Government because it is the prime way in which we see our meeting the Royal Navy's requirements for a STOVL [Short takeoff and vertical landing] follow-on to our present Sea Harriers...So JSF is a very high priority for the United Kingdom.
Confidence. The United Kingdom Government has a rather high confidence in this program, principally because of the attention Dr. Perry and Dr. Kaminski have explained, the attention that this program devotes to affordability. How to achieve the technological advance that is required at an affordable cost is a problem for defense procurement machines on both sides of the Atlantic. We think it is being extremely well addressed in the JSF program, so our confidence in JSF is high.
Thirdly, partnership. The United Kingdom Government is very satisfied with the full consideration that has been given in this source selection process to the Royal Navy's requirements. The United Kingdom Government has been fully and satisfactorily involved at all stages of this selection. We are confident that an equitable and significant share of JSF work will go to U.K. industry, and we believe there's a very real determination -- I speak for the British team -- but there's a real determination in both parts of the JSF Team -- American and British we think -- to make this U.S./U.K. collaboration a significant success.
Defense.gov Transcript: DOD News Briefing
Clearly there was enough involvement by 1994 for BAE to join McAir's "dream team", which meant significant contact with Wiechmann's very sensitive stealth tech in the Phantom Works.