We reported yesterday on a rumour that the next Technical Preview build of Windows 10 Mobile may make the huge jump to 1051x, a massive increase from 10166 currently in public circulation.
Now ITHome has posted proof, with a screen shot from a Windows 10 Mobile handset in China being upgraded to the new OS build, 10512.
A new build is expected to be released as early as this week. As of yet we do not know what features it will contain, but at the very least I expect a more polished, stable and performant OS as we head towards the final release in October/November.Source
Thanks DH Dog for the tip.