Possible Clues:

• In completion, much is coming up about significant letter
• Retired group touring Paris, perhaps as a climax
• Charge, briefly, involves money invested on top of everything else
• As a finish to hatter's ambition?
• What's more, many back taking on Brussels, for example
• Time round Great Lake as the final thing
• The final insult? Charge cut by 25 per cent eats funds
• As unpleasant climax, left to trail Londonwards perhaps
• As a (frequently unwanted) climax
• On top of everything else, item for auction rejected across London, for instance