It's far from official, but Microsoft corporate vice president Dan'l Lewin, who handles strategic and emerging business development, has hinted at the Windows 8 release date as likely to be early next autumn, making much the same calculation TechRadar did.
UPDATE: Check out our hands on: Windows 8 review
Speaking at the start-up LAUNCH event at the Microsoft Silicon Valley campus Lewin suggested "we will be in market - if you look at the crystal ball and just say what happened in the past is a reasonable indicator of what our forward looking timelines will be and just speculate - we've made the point about having a developer conference later this year, and then typically we enter a beta phase, and then in 12 months we're in the market, so let's make that assumption."
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Asked why moving Windows to the ARM chip had taken Microsoft so long after other tablets had come out, he acknowledged Vista had slowed the Windows division down ("we got a little behind on that, I would say") but said Microsoft had to take into account the large number of people using Windows already.
"We have a commitment to our installed base. With Windows 7 on a huge number of devices, we have a very sound and terrific baseline. Given the scale, we have a very strong belief system about that commitment, and a very large customer base that thinks about managing these systems; so systems management, enterprise infrastructure, all those kinds of things."
Consumers are also going to care about tablet security, he believes, and that's why it makes sense for Microsoft's tablet OS to be Windows rather than Windows phone.
"Our strategy is a statement about phones and tablets being more or less the same thing. I think tablets are big phones, more or less and I think they will want, over time, some of the capabilities that PC architectures have.
"They want the security, they want the manageability - especially if you are an enterprise buying large volumes of these things, but I think consumers over time want to know about those things as well. Our approach with the tablet play being based on PC architecture, rather than [adding to] the phone architecture, I think is the right one."
Can Windows tablets can catch up with iPad and Android sales after that long? "I think it will just be a race once we get in the market." The design of the Windows tablet interface started before the iPad came out, he said: "We knew where we were going, we just have to get there faster. We're executing as fast as we can."
Lewin also hinted at multiple tablets from PC makers rather than the single Microsoft tablet we've heard rumours about. "Clearly there will be a great installed base of iPad and other tablet devices but it will be incumbent on us and our hardware partners to prove those form factors and use cases, and the battle will be on in the market for what the consumers want to use."