Garthwaite's work is closely associated with the mid-18th century fashion for flowered woven silks in the Roccoco style, with its new emphasis on asymmetrical structures and sinuous C- and S-curves.
From 1742–43, Garthwaite's work—and English silk design in general—diverged from French styles, favouring clusters of smaller naturalistic flowers in bright colours scattered across a (usually) pale ground.
The taste for vividly realistic florals reflects the advances in botanical illustration in Britain at this time, and can be contrasted with French silks of the period which show stylised flowers and more harmonious, if unrealistic, colourations.
[10][11][12] Spitalfields silks were widely exported to Northern Europe and especially to Colonial America,[10] which was prohibited from trading directly with France by Britain's Navigation Acts.
[15] A gown currently preserved at Colonial Williamsburg was made sometime between 1775 and 1785 with the silk lampas that Garthwaite designed in 1726-28, which was passed down in an American family for around fifty years and reused for three generations before being assembled into the wedding dress that is now in their collection.