Bidspirit auction | Pre-philately. Letter written in Montemor-o-Velho

Pre-philately. Letter written in Montemor-o-Velho on 10.5.1806, marked MONTEMOR-O-VELHO, MMv1 in sepia, rar.6, to Porto, handwritten postage of 25 reis. This is the oldest known Montemor-o-Velho postmark, very well marked. MR and MB.