They do have a UPS... but apparently it was the UPS failing that caused the power cut! They probably got the UPS bypassed pretty quickly but if the playout system had got corrupted as has been suggested that would explain why they stayed out of Yalding for a while. Just to correct what a number of people have said based on what Vernon said when he came back on air - they weren't in Broadcasting House but Western House, which is home to Radio 2 and 6 Music. Switching back to Yalding shouldn't necessarily mean a break in programmes. The way they would do it is to fade up the Western House studio as an outside source in the Yalding Studio, matching the levels, then get London Control Room to switch Yalding back into circuit. Then drop the fader with Western on it when Yalding are ready to take over. This would have been how they got Western House on air cleanly off the back of the emergency tape. The "tape" plays from an area in BH controlled by LCR. They would have fed a seperate feed of the tape to Western, then switched Western into circuit on the Radio 1 distribution so they could leave it cleanly rather than crashing out of it. (This is a reverse of how they hand between studios - Scott Mills fades up Zane Lowe's studio, then when Zane is up and running they switch his studio to feed the distribution directly. This is done internally without needing LCR to do the switching.)