Possible Clues:

• Embarrassed look a flasher may get, on reflection?
• Problem in flash photo initially exposed in colour again
• Overnight flight to America which affects pupils
• Overnight flight has heads of European delegations enthusiastically getting stuck into whisky
• All-night flight
• Flash-induced effect on photo
• Rudd's colourful feature
• Photo flaw requiring, ultimately, change in colour again
• It departs late at night
• Old-fashioned advice you had, making cheap whiskey