From the Knit Rowan website:
Crochet this pretty overlay, the member’s exclusive free pattern for February 2015. Designed by Marie Wallin using our luxurious Fine Lace (baby suri alpaca & fine merino wool), this slip is constructed using three types of crochet motifs and will transform a simple dress.

Finished chest width dimensions:
44: 63 cm
17½: 25 inches

Yarn information:
Photographed in Porcelaine 928
2, 3 skeins
874, 1311 yards

Gauge notes:
Completed motif A measures 10 cm (4 inches) in diameter using recommended crochet hook.