An Elvish delight. This costume consists of a soft, brown shirt and dark trousers. The trousers come with brown boot covers to match the shirt (so no need to worry if he wants to wear his trainers with this).
The outfit has a jaunty pointed hat and a belt. This costume is suitable for Christmas plays as a festive Elf, or if accessorized with a toy dagger your Elf becomes a woodman from the stories of the Brothers Grimm or Hans Christian Andersen. Alternatively, equip him with a bow and a quiver of arrows or a toy sword, and you have Will Scarlett or one of Robin Hood's other Merry Men.
So this versatile costume is suitable for winter parties, general dressing-up, or for a wide range of characters drawn from classic children's stories on World Book Day (for example, an elf from Tolkein's Lord of the Rings).