The Oxford is a type of leather shoe.  These shoes were originally from Ireland and Scotland and are typically quite plain with (at most) small perforations as detail.   According to Hoyle, when it comes to shoes and ornamentation, less is more.

Straight-laced :

1)  Refers to a method of fastening two pieces so that the laces span straight across rather than making a crisscrossed pattern.

2) Oxford English Dictionary definition: having or showing very strict moral attitudes.

Fact Credit: Wikipedia.org; askoxford.com

Image credit: Maison Martin Margiela via tresbienshop.net