One of the most accurate and reliable kinds of alarm clocks are radio controlled. They work by synchronising their time with a radio signal which transmit’s the correct time. In the UK this radio signal comes from Cumbria and is tuned into an extremely accurate atomic clock. The main benefit of radio controlled alarm clocks is that you do not need to set the time, as the clock will automatically pick up the signal and adjust its time by itself. The other benefit is that radio controlled alarm clocks also adjust the time when the time shifts during the seasons, I.e. when British summer time ends, the clocks move by an hour, this would automatically be done by these types of alarm clocks.