North-facing bathroom contains very round moulding (5)

I haven't cracked this one yet — but the brilliant team at Times for the Times have:

North facing instructs you to reverse LOO for bathroom, then you insert V[ery] and add another round O. “A moulding with the rounded part composed of a quarter of a circle, or of an arc of an ellipse with the curve greatest at the top”. Just so you know.