I think the end product is more important than the terminology.
We have white and brown things we call 'gravy' in America. It seems to be defined by the consistency more than anything.

Maybe our 'gravy' has flour as a thickening agent?
( Syncubus Yarr! Ye'll be walking Planck's Constant! [GMT-5], Thu 10 Jan 2008, 22:17, archived)

Quite possibly
cornflour is often used for this.
( wynoh kills threads by his mere presence, Thu 10 Jan 2008, 22:19, archived)