UK receives first F-35 stealth fighter jet from US
It has been a long and expensive wait, but Britain has now been handed its first Joint Strike Fighter jet, also known as the F-35.
Defence Secretary Phillip Hammond flew out in person to the searing heat of Fort Worth, Texas, for the official handover ceremony from its US manufacturer Lockheed Martin.
He says it is "the best warplane money can buy". But it is an eye-watering sum - the current cost of each jet is more than £100m.
After watching Britain's first F-35 take to the skies, Mr Hammond said "this is money well spent".
He said it would give the RAF and Royal Navy "a world class fighting capability" with the ability to "project power" off the two new aircraft carriers now under construction, anywhere in the world.
So is it worth it? The UK is buying the short take-off and vertical landing variant - STOVL for short.
It is the heaviest and most expensive of the three versions of the plane, carrying a lift fan propulsion system for its "jump jet" capability, which it needs to land on the Royal Navy's new carriers.
The most obvious comparison is with the scrapped Harrier jet it is replacing.
The Harrier had a range of 300 nautical miles; for the F-35 it is 450 miles. While the Harrier could reach a speed of 650mph, the F-35 can fly much faster - more than 1,200mph.
The Harrier had no radar transparency or stealth capabilities, but the F-35 has both. Its acute angles and special coating make it difficult to detect on any enemy radar.Weapons load
BAE Systems test pilot Peter Wilson said the F-35's stealth technology is "worth its weight in gold".
It means a pilot can enter and leave a war zone while staying safe.
In theory, it can also carry a heavier weapons load than the Harrier, although the F-35B "jump-jet" is the least capable of the three versions of the new plane.
But even with its cutting edge technologies, the F-35 has flown into a storm of criticism, particularly in the US where it has gained unwelcome notoriety as the most expensive equipment project ever undertaken by the Pentagon.
The US is spending around $400bn (£254bn) to buy 2,500 F-35s for the navy, air force and marine corps.
It is estimated that the total cost of buying, operating and maintaining the planes over the next 30 years will be $1tn.Serious problems
Winslow T Wheeler, at the US Center for Defense Information said it was a "gigantic performance disappointment". Not as stealthy as the F-22 for example.
He added: "It's the counterintuitive problem of paying a huge amount of money thinking you're getting a Lamborghini or Ferrari: You're not, you're getting a Yugo"
He was referring to the cheap, mass-produced cars made in the former Yugoslavia.
That may sound extreme, but even a more measured report by the US Government Accountability Office (GAO) highlighted serious problems including the management and development of more than 24 million lines of software code in the aircraft and faults with the helmet-mounted displays.
The GAO report warned that "most development flight testing, including the most challenging, still lies ahead".
The F35 may be more like a thoroughbred race horse, but so far it has proved just as temperamental.
The F35 - which will be called the "Lightning II" by the RAF and Royal Navy - is still a long way off from being battle ready.Industry involved
Though British pilots have already been involved in the test flying programme, they will not be flying the plane off UK bases or the two new aircraft carriers until 2018.
And it is still not clear how many planes the UK will buy.
The last Labour Government said the UK would buy 138 planes but Mr Hammond has so far committed to purchasing only 48.
That number, over time, is likely to increase - not least because British industry is heavily involved in the project.
The tail section of every plane is being made by BAE Systems. Overall the UK has a 15% share of the work, enough to sustain more than 20,000 jobs.
The hope at the Ministry of Defence is that, with time, the cost of the plane will come down and the technical problems will be resolved - and that, in the end, this will not go down in history as another expensive MoD mistake.