In conjunction with BBC R&D experiments and demonstrations at the 2014 Commonwealth Games, an explorative field trial was conducted with a live zoomable UHD video system. The unique field trial featured the world's first live tiled streaming of 4K UHD video to end users. During the trial, we studied and evaluated the attractiveness and novelty of an interactive UHD application, and investigated system design aspects of a live UHD tiling system. In this paper, we evaluate the overall perceived quality of experience (QoE) of the application and to what extent the QoE depends on system factors and/or network conditions. We observe that interactive UHDTV is well received by users, but the delivered experience may decrease in presence of low bandwidth availability.