The Treflach Troop go to the Seaside, page excerpt

There is a very small typo/error that has now been turned into a game. Can you spot the mistake? It's very, very small so look carefully.
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The Treflach Troop go to the Seaside, page excerpt

There is a very small typo/error that has now been turned into a game. Can you spot the mistake? It's very, very small so look carefully.
Ref:
Date:
Location:
Photographer: