Watch List notes:

ROMAN AND BYZANTINE COINS

Q. Junius M. Caepio Brutus, 43-42 BC. Denarius (Silver, 17mm, 4.18g 8), mint moving with Brutus in Greece. LEIBERTAS Head of Libertas to right, her hair bound in a bun at the back. Rev. CAEPIO BRVTVS PRO COS Plectrum, lyre and laurel branch tied with fillet. Babelon (Junia) 34. Crawford 501/1. Sydenham 1287. A splendid, attractively toned piece. Extremely fine.

Ex Numismatica Ars Classica 51, 5 March 2009, 109.
This coin clearly must have a much longer pedigree than just the one sale listed here: the toning and the fabric indicate that it has had a long history in collections.