He puts forward a very deeply researched and scholarly derivation, starting with a Latin root currere which gave the Latin cursor for runner, and the family name of the Cursores . The Latin words were carried across into Italian and French. In Italian there was corsa for a course and corsiere for a courser or horse. In Old French there was corsier or coursier , meaning a steed, corsour meaning running, and Le Corsour was a name for a horse-dealer. SBGC quotes from two old sources.
Subsequent works dealing only with the names in Britain follow the Middle English derivation.
However there are certainly instances in the Shropshire Peace Rolls of 1400 of men referred to as Corviser by occupation as well as by name, and there is a family in north Shropshire which appears in Parish Records in the l6th century as Corviser, becoming Corser by the 17th century. On the other hand, there is a family in south Shropshire which appears in 16th century Parish Records as Corser. In the IGI there are only 9 instances of Chaucer in the West Midlands area, in Shropshire and all dating from the 14th century. From the above it seems clear that the majority opinion is that the derivation in most cases comes from a connection with horses, horse dealing and riding. This harks back to SBGC's derivations which opened this section.