Why did my radio-controlled clock move to summer time at 2 a.m., one hour late?
You are correct in implying that British summer time begins at 1 a.m., this is when the times signaled by the MSF radio service and the Truetime telephone time service are altered. In fact, because the information is sent in advance, the MSF signal has already changed during the previous minute, and the Truetime signal changes during the previous second. However, only mains-powered radio-controlled clocks are likely to be continuously checking the MSF signal. Radio-controlled clocks typically check the time only every hour, or every two hours, and radio-controlled watches only perhaps three times a day. This is to conserve the battery, as the reception unit takes more power than the clock/watch mechanism. So some radio-controlled clocks or watches may not ‘realise’ that the time has changed until an hour or more later. How long will a battery last in my clock/watch? Generally with clocks batteries will last for 12-18 months dependant on battery quality and operating temperature. For wa
