Kippax were indebted to Chris Baldwin, who despite struggling for long periods dug in to hold the innings together with a gritty 70.
Jake Vanoorschotz was the other main contributor with 46 as the visitors amassed a challenging 207-9.
Pick of Preston's bowlers was Darren Childe, who was unlucky to pick up only two wickets. Mark Mosby claimed 4-48 and Adrian Sharp picked up a brace.
Preston made a steady start to the reply, with openers Johnny Milner (27) and Lee Smith (29) putting on a half-century for the first wicket.
But the introduction of spin duo Vanoorschotz (3-47) and veteran Dennis Ruddick turned the tide as wickets fell at regular intervals. Only Russ Milner (26) and Childe (32) offered any worthwhile resistance as Preston slipped to 170 all out.
A century from James Liddle provided the back-bone of South Milford's first win of the Division Two campaign.
The opener cracked four sixes and 12 boundries in an unbeaten 146-ball knock of 103 not out.
Liddle and skipper Roger Hodgekiss (42 not out) shared an unbroken 122 third-wicket stand as Milford posted 223-2 against Old Leodiensians.
Simon Horner then produced his best bowling figures for the club - a sizzling 6-21 return off 11.4 overs that included two spectacular caught and bowls - to spearhead a 36-run win.
Defeat was tough on Leos' skipper Chris Huby, whose battling 68 looked to have turned the game in their favour.
Not until he fell to a magnificent diving catch by Jonny Booker could the home side breathe easy.