Thankfully, Edinburgh airport has relaxed it liquid rules. You are now allowed up to 2 litres, across one or more containers and they stay in your bag while going through security.
That specific example probably originates from Tolkien.
J. R. R. Tolkien: A Biography:
> When [Tolkien] was about seven he began to compose his own story about a dragon. ‘I remember nothing about it except a philological fact,’ he recalled. ‘My mother said nothing about the dragon, but pointed out that one could not say “a green great dragon”, but had to say “a great green dragon”. I wondered why, and still do. The fact that I remember this is possibly significant, as I do not think I ever tried to write a story again for many years, and was taken up with language.’
I remember watching a documentary about the Ordnance Survey department and it mentioned that the artists would hid their name in things like rivers because they did not get official credit.
https://www.artsy.net/artwork/ward-shelley-history-of-scienc...