Bill and Ben will be modelling white harness, with matching plumes.

I'll give her the pony-chaise and the white harness, and she shall drive herself, if she likes.

If she's a young one, either I know nothing of women, or the pony in the white harness will bring her to the picnic.

"A lady from London; connected (if you'll allow me to jog your memory) with a pony-chaise and white harness."