Food irradiation is a non-health-affecting way of killing bacteria in food in order for it to be made shelf-stable for retail sale. Obviously, it is less popular then other approaches but still an interesting strategy nonetheless.
Does the UK have an indigenous people?
The Celts came from Central Europe starting from 1500 BC. As far as there being an actual native people, it does not appear that there were.
World Directory of Minorities and Indigenous Peoples – United Kingdom
Who Were The Celts? A No-BS Guide To Their History And Origin
When was the first traffic light introduced?
From Traffic light control and coordination:
The first automated system for controlling traffic signals was developed by inventors Leonard Casciato and Josef Kates and was used in Toronto in 1954.
What? How? Wonder. 
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