Placed for the 2019 DST event.
William Willett was a British builder, most famous as a proponent of British Summer Time, a precursor to Daylight Savings Time. He did not invent the concept- it was used in the ancient world, and Benjamin Franklin satirically suggested returning to that ancient concept. The first modern person to seriously promote the idea was George Vernon Hudson, but Willett tirelessly pursued the idea, even getting support in Parliament. Unfortunately, he died in 1915 before seeing his idea adopted as a coal/energy saving method during the Great War.
The cache final should be straightforward, standard hide. See the hint if you need a nudge.