As I have reflected on the limited facts at hand, one that has stood out is that "all pieces were pre-sold prior to production." The only way I can explain this is that the special event with Andrew Thomas, either hosted by or for/with him, was in fact a fundraiser conducted in conjunction with IWC. Then, one can deduce that at the fundraiser, either a rendering or prototype of this curious watch was brought out, and those who were invited and attended the fundraiser, as part of the fundraiser, were given the opportunity to buy one of these watches, proceeds of which would go to assumed charity/foundation that was part of the event... In this scenario, 27 attendees committed to buying the watch. Hence, all were pre-sold prior to production, and the curious number of 27 pieces was not a predetermined run number, just how many were purchased at the event. And afterwards, when IWC actually assembled the watches, they only produced 27. Maybe the caseback thus states something like xx/27.