A list of potential substitutes, if you can
YarnStories Linen 2 ply - Ravelry
Waxed Irish Linen Thread 4 Ply - TinkerCrafts
Ravelry: YarnStories Linen 4ply
LUGANA 25 Count Evenweave Zweigart Fabric for Needework - Sweden
4/12 Natural Wet-Spun Tow Linen - Yarnorama
40 Ct Newcastle Evenweave Zweigart Linen Fabric - Israel
Waxed Irish Linen Thread 4 Ply - TinkerCrafts
Yarn Stories
Ravelry: YarnStories Linen Thread
YarnStories (on ) Linen 3-ply
Ravelry: YarnStories Linen 4ply
28 Ct Cashel 100% Linen Evenweave Zweigart Fabric - Finland