The United Kingdom has successfully launched a satellite using a rocket that they built themselves exactly once, in October of 1971. The Prospero spacecraft operated for two years and was contacted annually until 1993, and now British scientists want to wake it up again for its 40th anniversary.
40 years is a long time to be up in space, but the Prospero satellite almost didn't make it there at all. Britain's satellite launch vehicle was called Black Arrow, and of the first three launches, two ended in failure. The entire program was scrapped in July of 1971, a few months before the Prospero launch, but since the rocket had already been shipped to its launch site in Australia, the decision was made to try and send it up anyway to see what happened. As it turned out, everything went splendidly, and that one single successful launch was essentially both the beginning and the end of the British domestic space program.
The Prospero satellite itself was designed to test solar cell efficiency, measure micrometorites, and study the environment of low Earth orbit, which it did for a couple years. For the next 25 years, Prospero was checked in with about once a year to see how it was doing, although it was officially deactivated back in 1996. Deactivated or not, it's still wandering around up there, powered by the sun and in an orbit that isn't expected to decay for another hundred years or so. Armed with the right codes, a team from University College London is going to try to ping it on the satellite's 40th anniversary this October.
If they can make contact, it's remotely possible that some of Prospero's experiments are still working, but even if they just get back a lonely little "hello," it'll still be a big moment for Britain's one and only 100% home-grown satellite.
For more on the Black Arrow program, there's a documentary about the Prospero launch and the technology and people behind it on YouTube.