This invention is only concerning mains-driven electic clocks that do not use quartz. Bear with me!
Virtually clocks that run off mains electricity tell the time by working of the speed of the alternating current being passed to it. If memory serves me, the current passes between + and - exactly
50 times a second -- hey presto -- the clock can count these for accurate time keeping.
My device plugs into your plug socket, then you plug your clock INTO the device.
It's operation is simple .. the device has a 'set once' date and time. On the date that the clocks move forward an hour, in the middle of the night, my device slightly speeds up the A/C that is being passed to the original clock. Say 25% quicker, for four hours (although naturally the device is still reading the electicity in at +- changing at 50 times a second).
When you wake up in the morning, your clock - dutifully counting the speed of the A/C chang, will display the correct, new time! With no need to alter it manually! The clock would have added an hour as my device passed it exactly the right number of more +- cycles!
Naturally later in the year a 4 hour period in the middle of the night slows the A/C down to 25% slower -- and the clock will lose 1 hour as it does what it always has done -- rely on the speed of the +- change in the AC!
Never bother with the manual change of your electic clock time again - without having to chuck the perfectly good £100 electric clock away to buy a completely new one that does the 'get the time through the radio' thing!