Update: Some owners have also reported to us that the update is rolling out in France, Germany, Italy, the Netherlands, and other European countries as well.
HTC is steadily dishing out KitKat to HTC Ones all over the place, and now it's the UK's turn. The company has started the Android 4.4 rollout today, which will continue over the next several weeks. It might not yet be your turn in line, but that doesn't mean there's any harm in checking right away.
We started rolling out Android #KitKat 4.4 for the HTC One in the UK. Settings > About > Software Updates > Check now!
— HTC UK (@HTC_UK) February 24, 2014
According to the HTC's software updates page, Android 4.4 is being pushed out to Vodafone, O2, and Three customers. Those running their HTC Ones on EE may have to wait, as that OTA is still shown in the "integration" stage of the process.
In addition to the latest version of Android, this update comes with Sense 5.5, which introduces white system icons and an extra layer of polish on top of HTC's custom interface. There's plenty to keep One owners contented with their handsets until the next version of Android comes along, or until we get our first look at the latest take on Sense at HTC's upcoming March 25th event.