Possible Clues:

• Noted a turn of a boy that went off
• Noted date had switched and set off
• Exploded
• Set off from school wearing old hat
• The weight at the inside, indeed, was set off
• Exploded, being old-fashioned about public school
• Went off semi-detached, well-known retreat
• Set off breaking into old school
• In action, youngster touring North America set off
• Went off with a bang