The Hackett London store has an extensive range of blazers, formal shirts, polos and casual wear. They also have trousers and chinos, and accessories to style them with. Their collection is perfect for fancy occasions, or for someone who likes to dress smart and professional.
Their online platform has formal wear even for kids (even for two year olds)!
All in all, if you get in the store, you'll definitely return as a gentleman (or a gentle-baby).