I can find about 106 distinct Child ballads on the various MacColl ballad series on my shelf, and a few odd others. I'm still missing a few of The Long Harvests and one of the Riversides, so I'll increase my earlier estimate to about 115 - 120 separate items.

Drift: I suspect that I'm not the only one who has picked up a few duplicates along the way. Anybody interested in some trades? There's an e-mail listserv for collectors of MacColl material that might be a good channel for that. The address is in the discography linked a couple of messages back.