Dissertation done, copied, waiting to go to the binders to be made pretty. And, happily, the conclusion is that it (i.e. the Song of Songs) is all about the Lord Jesus.

I can't summarise it better than by borrowing Raymond Ortlund's description of John's purpose in Revelation:

The suffering church militant of this present evil age is to cultivate one great impulse, throbbing in her soul, viz. an aching longing for the Bridegroom to come to her, to take her in his arms, with nothing within herself to wrest her away, and to be held there for ever.

Amen. Come, Lord Jesus.