Todd made 65 at the top of the order from 120 balls with 12 fours as Horspath posted 184 all out after being put in to bat.
He put on 90 for the second-wicket with Robbie Eason (30), but after they were dismissed in quick succession the innings fell away and it took a breezy 28 from Charlie Turner to take the hosts to their final score.
Ben Denton pegged the home side back with 5-19. But Horspath's bowlers then got stuck into Downs' batting as the visitors crashed to 101 all out.
Erasmus Du Toit (4-19) was the chief destroyer, well supported by opening partner Subhan Javaid (2-18) with Turner, Luke Heritage and Christopher Hofen picking up a wicket apiece.
The win keeps Horspath in second place - four points behind leaders Challow & Childrey.
Posted by: Russ