Possible Clues:

• Bath water unit
• In decimal, it represents just over 1pints
• Fired about a quantity of liquid
• Volume illuminated with a little reading
• Rather drunk on somewhat under two pints
• Settled on a non-imperial measure
• That gives one the measure of the Continent that gets lighted about it
• Literature on relativity at first's given E = Mcc?
• Londoner's petrol unit
• Size unit of an English soda bottle