The Kettle Hat has remained the cornerstone of cranial protection, essentially unchanged, over c.800 years of its history.
Its enduring qualities are
- it protects your head
- it can be used, as its name suggests, as a receptacle in which to 'brew up'
- it functions as an admirable 'chamber pot' when not being used as above
The phrase 'keep it under your hat' - ie keep something secret - is almost certainly derived from the practice of English archers to keep their bow strings dry by keeping them protected from the elements. The most obvious way to do this was to keep them under their hats.
I'm not entirely sure if this in any way brings the debate any further.
