Heritiers P.de Marcilly
Pierre-Antoine, the abbot of Marcilly?
Pere? As in "father," "priest" or "abbot."
Sometimes P. in front of a name just means older or respected.
1) Last mention of P.de Marcilly in the Guide Hachette des Vins seems to go back to the year 2000, the Guide indicating they are part of the group Boisset, phone # 03.80.62.61.61
2) A quick search produces record showing in fact phone above corresponds to Jean-Claude Boisset
3) The Boisset site http://www.boisset.fr/ makes no mention whatsoever of P.de Marcilly