Short answers, pulled from the story.
The English word inch emerged from the Latin term uncia, meaning one-twelfth or Roman ounce. Early phonology shifted the vowel through umlaut and consonants changed via palatalisation to match Old English patterns.
Edward II issued a statute in 1324 defining the inch as three grains of dry round barley placed end to end. King David I of Scotland proposed defining the Scottish inch by the width of an average man's thumb at the nail base around 1150.
The British Standards Institution adopted exactly 25.4 mm for their inch in 1930 while the American Standards Association followed suit in 1933. The United States officially joined the agreement on the 1st of July 1959 creating a new standard slightly longer than the old imperial version.
Public sector guidance since the 1st of October 1995 mandates inches as primary units for road signs in the United Kingdom. Display screens worldwide utilize inches as the official Japanese standard for electronic parts and Continental Europe treats inches as industry standards for televisions and computer monitors.
ISO 31-1 Annex A establishes in as the international standard symbol for the unit. Traditional notation uses a double prime often approximated by a double quote symbol while engineering purposes commonly employ decimals to three or four places instead of traditional fractions.