It's deerfield embroidery, but not that Jacobean looking. And using more than just blue and white threads. So not technically deerfield, but inspired by it.
Deerfield embroidery is named for a town in western Massachusetts in the US. The story goes that in days of old, two women founded the Deerfield Society of Blue and White Needlework to replicate some old Jacobean embroideries for posterity. But they were forced to adapt to the realities of the time and used the blue and white linen and flax threads that they could get their hands on.
The crewelwork designs popular in that era had already been adapted to use less thread, another nod toward practicalities in deerfield embroidery. And so Mock Deerfield draws on elements of Jacobean or crewel embroidery but in a more contemporary design - the elaborate floral element is pared down and the larger trellis left unadorned.
Stitches commonly used in deerfield embroidery spring from those used in Jacobean pieces - stem, feather, fly, seed, herringbone and others. And you'll find these used in innovative ways in Mock Deerfield. Along with, of course, trellis work and multiple rows of chain stitching.
Adding more colours isn't really a new thing, as different colours were introduced to traditional deerfield embroidery as and when new natural dyes were discovered and used to colour thread. It does keep the embroidery interesting to do, though.