Aha! Thanks Gail, I didn't know about DATALENGTH! That was the tool I needed to get to the bottom of it.

Nearly all the space is used by the _FullCommand column. Most records are quite reasonable (from a few bytes up to a few KB), but there are just over 100,000 records in there with more than 1MB in that column. When I cut the retention in half none of those big records were amongst the data to be deleted.

I can track down the statements (they are all of the same form, and I have a good idea where to look now) and determine what to do about them from this point on...

Thanks again, you've been a great help 🙂

Cheers,

Dave.