Confirm and deny
Confirm that commission, that is, and deny the rights-grabbers their ill-gotten spoils. Don't do as the Freelance editor and all too many freelances do, and accept work on the strength of a phone call. Do as the Freelance says: fax back a Confirmation of Commission form making your terms absolutely clear.
The Creators' Copyright Coalition, an informal grouping of organisations representing journalists of various kinds formed in response to the Telegraph rights-grab attempt in 1995, produces just such a form. You can download a copy to print (using the free Acrobat program) from the Rate for the Job web pages at www.gn.apc.org/media/rates or contact the Freelance Office to get a slab of pre-printed forms.