Timeliness of notice of claim to excess carrier

“Does the failure to give notice to an excess carrier until after an adverse jury verdict constitute evidence of prejudice that forfeits coverage?”  Berkley Regional Ins. Co. v. Philadelphia Indemnity Ins. Co., 690 F.3d 342 (5th Cir. 2012).  The Court thoroughly reviewed Texas law about untimely claim notice, observing that it can void coverage if the insurer is prejudiced, but “[d]efining the contours of prejudice from the breach of a notice requirement . . . is not easy.”  It applied that general principle to excess carriers, and found that this carrier had raised fact issues about prejudice from untimely notice (here, after an adverse jury verdict), as it was unable to investigate the matter or participate in mediation: “The cows had long since left the barn when [the carrier] was invited to close the barn door.”