From the magazine:

Retro and vintage themes are playing an important role in home interior and fashion at the moment. In this cushion I have taken inspiration from the 70s, which introduced some trippy colour combinations. Flower Power prints went from fashion to homewares, with Scandinavian Marimekko taking the lead with bold colours & flowers. I have used a vintage fabric from Sweden from the 70s as the fabric backing (as an option to a knitted backing) to make the cushion special. There are plenty of fabric companies online where you can find that special piece you are looking for.

Backing fabric for cushion: 45cm x 65cm / 17.5” x 25.5”, if not knitting the backing.