From the magazine:
“This square is similar to a traditional granny square but worked entirely in trebles with chain spaces at the corners only. These form diagonal lines that cross in the centre of the square.”

This pattern is repeated through different issues of the magazine, differing only in the colours:

Issue 18: Maize, Redcurrant, Vanilla
Issue 37: Sailor Blue, Turquoise, Vanilla

NOTE: The picture shown in the magazine of the single block shows only 3 rows of the final colour, but if you look closely at the picture of the finished throw, they have 4 rows of the final colour. Without this extra row the square will be smaller than the required 13cm.