challenge: Where were the BL 12-inch Mk VIII naval guns from HMS Illustrious used for coast defence from 1921 to 1926?
  
  A. North and south of the mouth of the River Thames in southern England
  B. North and south of the mouth of the River Tyne in northeast England
  C. North and south of the mouth of the River Severn in western England
  D. North and south of the mouth of the River Mersey in northwest England
  Answer: 