Laburnum.

If I may continue with the Bodnant theme briefly, one of my favourite features of the garden is its laburnum arch- as shown above, it really is stunning. We have two laburnum trees at home, but they're rather more wild!

Laburnum, "Golden Chain".
(Decidous tree.)

Planting: Autumn or spring.
Flowering: Spring.
Aspect: Full sun.
Hardiness: Hardy even in very cold winters.

Notes: In J.R.R. Tolkien's 'The Hobbit', Bilbo describes some of Gandalf's fireworks as "laburnums of fire", hanging "in the twilight all evening!"