The origin of the name "le Sire" would seem to be "le Scieur" diminutive. "Scieur" being an ironic nickname of Lord. In the parochial registers we find various spellings for the same person: to the baptism, to the marriage and the burial. It is probably, to the certain vicar fantasy, or according to the pronunciation of the declaring of the "s" and none "z". Thus, one discovers written form: le Syr, li Sire, le Chire, Sire, Syre, Lesire, Lesir, Lesyre, Lesyr, Lecire, Lefsire, Lessire, Lessir,... "Le Sire's" passage to "Lesire" would be presumably due to a contraction of the two words.
It is to Rebecq (township of the Brabant Wallon, situated between Brussels and Mons, in Belgium) that one finds this family's the oldest traces, notably in the documents embodying the political proxies. One discovers there: Jehans li Sire that was an alderman to Rebecq of 1310 to 1330; his grandson, Bauduin li Sire, of 1368 to 1398; Pierart le Sire, of 1448 to 1450; and Jehan le Sire of 1513 to 1541.
Most the other members of this branch are mentioned in the directory of the Nobility Belgian of 1877. We learn as well as Jehans le Sire got married to Nivelles toward 1465 and installed himself of it. Then, Pière the old bought the forge of Sart-Eustache in 1570. His son, Pierre the young, emigrated of Nivelles, after the seat that of it was made by the Spanish in September 1579, to settle to Namur, where he acquired middle class.
The grandson, François, got settled to Sart-Eustache. He was ennobled July 29, 1605, by the Albert archdukes and Isabelle, and received the lordship of Gougnies. Begin the lineage of the "de Sire" that would be extinguished according to the author of the A.N.B then of 1877. But possibilities of uniting necessarily are not located at the end, because these forebears were to the service of one or the other army, what supposes good of displacements, notably in Hungary and in Spain: to Castel, Calatrava,...