Update 24 Feb: Following a no-show at MWC, uSwitch brought the bad news that the Sony Xperia Z6 will not arrive at IFA either. But Sony has since clarified that it isn't ruling out the possibility of an Xperia Z6 at some point in the future. Read more in the Sony Xperia Z6 UK release date section below.
This time last year Sony was getting ready to take the wraps off a brand-new tablet (the Sony Xperia Z4 Tablet) and a mid-range smartphone (the Sony Xperia M4 Aqua), but not the Sony Xperia Z4 we had been hoping for. This phone was instead announced a couple of months later in May, but known as the Z4 only in Japan. Sony didn't dare give it the name Z4 in the UK, given that it showed only a small improvement over the Xperia Z3 it had revealed in September 2014. Instead, it became the Sony Xperia Z3+, and it was plagued not only with criticism from reviewers but overheating issues, too.
And so the rumours that a struggling Sony, which was laying off employees, could no longer maintain its tradition of releasing two flagship smartphone upgrades a year were seemingly confirmed. But if it were to launch just the one, would it use the Mobile World Congress tradeshow in late-February/early-March or IFA in September to announce its next phone?
At IFA 2015 Sony unveiled the much improved Sony Xperia Z5, along with Compact and Premium versions - the latter was the first smartphone we'd seen with a 4K screen. Sony had its game back, so we thought, but this alone was no confirmation as to whether it would be releasing one or two smartphones per year and, if the latter, whether the Z6 would therefore arrive at February's MWC 2016.
Sony did hold a press event at Mobile World Congress, and obviously we now know that it did not announce the Xperia Z6, instead taking the wraps off the Xperia X and XA. Also see: Best smartphones 2016.
Sony Xperia Z6 UK release date rumours: When is the Sony Xperia Z6 coming out?
Sony Xperia Z6 estimated UK release date: 2 September 2016
New Sony Xperia Z6 estimated UK release date: Unlikely, but never say never
As we mentioned above, Sony held a Mobile World Congress press conference on 22 February, but the Xperia Z6 was not announced. Our money was on an IFA 2016 release for the Sony Xperia Z6, which would mean an announcement on or around 2 September 2016.
We were wrong it would appear, because the Sony Xperia Z6 is not coming now - or ever. According to a uSwitch exclusive interview with Jun Makino, senior product marketing manager at Sony Mobile, the Sony executive told uSwitch: “I can't comment on the future, but we will not be releasing a Z6."
uSwitch reports that "Pressed further, he reiterated that 'there will not be a Z6' and that instead the company is 'turning to the next stage, with the Xperia X series'."
Sony has since clarified to Tech Radar that it isn't entirely ruling out the possibility at some point in the future, but that doesn't sound too hopeful to us.
You can read our review of the new Sony Xperia X and XA here, and read on below for a round-up of the rumours of the phone that apparently doesn't exist.
Sony Xperia Z6 UK price rumours, versions: How much will the Sony Xperia Z6 cost? Will there be a Sony Xperia Z6 Compact or Premium?
We haven't heard any rumours on the Sony Xperia Z6's price, but Sony doesn't deviate far from £550 for its Xperia flagships (or at least it hasn't done so in the past). Should it announce a Sony Xperia Z6 Compact and Sony Xperia Z6 Premium, as it did with the Xperia Z5, we'd expect to see prices of aroud £430 and £630 respectively to match the Z5 range.
One of the complaints noted by reviewers of the Sony Xperia Z5 Premium was that the 4K screen wasn't available at that resolution for all tasks, and that ideally it should have been a feature in the standard Z5. With the Z6 we could well see Sony incorporate the 4K screen tech into its standard model, especially given that more mobile manufacturers are likely to follow in its 4K footsteps over the coming year. In which case, we wouldn't need a 'premium' Sony Xperia Z6. We would still like to see a Sony Xperia Z6 Compact, however, since not everyone wants a large-screen phone and Sony has proven the best there is at reducing size without compromising on specs and features.
Sony Xperia Z6 specification and feature rumours: What we want from the Sony Xperia Z6; what we expect from the Sony Xperia Z6
Most of the rumours circulating so far concern when the Sony Xperia X6 will be released, rather than its specifications. To our minds, that adds fuel to the theory that the Sony Xperia Z6 won't land until September - if its launch really were just a few weeks ago then no doubt we'd have heard more details by now.
Much of what you'll read below is speculation, based on what we've come to expect from Sony and what we know about the smartphone market in 2016. However, there has been one leak from Japanese site Docomo, which seems realistic to us. According to the site, the Sony Xperia Z6 will feature a 5.2in WQHD IPS display, a Snapdragon 820 chipset with Adreno 530 graphics, 4GB of LPDDR4 RAM, IP68 certification (waterproof protection), Bluetooth 4.2, 802.11ac Wi-Fi and 23Mp/5.1Mp rear/front cameras.
Those specs are listed alongside the following image, which may simply be a Sony Xperia Z5.
Below you can read what we think we'll see in the Sony Xperia Z6.
Design-wise we can expect something similar to previous Xperia phones since Sony seems to be continually sticking with the recognisable square shape. We'd like to see something a bit different, though to shake things up a bit - while maintaining that distinctive Sony style. Waterproofing is unlikely to be going anywhere, and the new fingerprint scanner will more than likely continue to reside in the power button.
It seems Sony has settled on the 5.2in screen size for its flagship Xperia range so it's unlikely this will change on the Xperia Z6. The resolution is much harder to predict with the firm sticking to full-HD so far instead of jumping to Quad HD.
We mentioned earlier that the Z5 Premium's 4K screen could make its way to the standard Z6, but actually a Quad-HD display would be a more logical next step for the phone.
It's widely anticipated that most high-end Android smartphones next year will come with Qualcomm's Snapdragon 820 processor and that's what we expect for the Xperia Z6. That said, it's been reported by Digitimes that Sony could be about to follow Apple, Huawei and Samsung in producing its own processors for smartphones.
You can bet there will be 3- or 4GB of RAM and likely 16/32GB of storage.
That might not seem like much but Sony is one of the big name phone makers to stick with offering expandable storage via Micro-SD card slot and we don't think that feature will be dropped.
Sony prides itself on long lasting battery life but we'd like to see the addition of wireless charging. With the Xperia Z6 arriving in 2016, reversible USB Type-C is pretty much a given.
The Xperia Z5 range got the first camera upgrade since the Xperia Z1 with the new 23Mp shooter so will the Xperia Z6 get another upgrade? We think not based on history, at least nothing major but Sony will likely make improvements.
As soon as we heard anything further on the Sony Xperia Z6 we'll update this article.
Read next: Best Android phones 2016.