One of the takeaways from today's UK press launch of the Lumia 640 and 640XL (reviews of both smartphones in progress at AAWP) was that Windows Phone 8.1 Update 2, shipping on the two new phones, will in fact come as updates to some existing devices after all. The spur in this case is the new USA 'kill switch' requirement, with Update 2 complying with the new law. Whether the update will make it to Lumias anywhere else in the world is debatable - after all, Windows 10 is only just around the corner, eh?

Beginning in July, the new USA law requires that all smartphones come with 'kill switch' technology to let their owner remotely disable it and wipe its data, in the case of a theft, effectively 'bricking' it. The law also requires that this kill switch be enabled by default when the user first sets up their phone. Although the user could still opt out, the default makes it likely that most people will leave the kill switch 'on'.

And of course, if thieves know that most new phones can quickly be 'bricked' by their owners in the event of a theft, they'll stop stealing them, as who wants to buy a brick?

Also in Windows Phone 8.1 Update 2 are HID support and a lot more, see out feature for a full breakdown. Again, the same components are also being baked into Windows 10, so in many cases it's a case of moving straight to that.

Having said that, I wouldn't put it past Microsoft to slip out Update 2 for a handful of other Lumias, such as other 830 variants and perhaps the Lumia 1520/1320, not least for business purposes. Watch this space!