This is a replacement WD key for W4 caravan locks. The key can be cut from the key code or a decent picture of an existing key.
The key code will take the following format:
The key code is usually stamped on the face of the lock.
Alternatively... the key can be cut from a decent digital picture of an existing key.
A picture like this taken from the top:
The new key will be stamped with the key code.