Used 2 strands held together. This was a quick project (finished in a couple of days, even with houseguest to entertain!) and the Greylock worked beautifully for it!

Modifications:

• used the 4.5 needles throughout; did not switch to 4mm for centre section
• made two halves and joined in the middle using Kitchener stitch, instead of joining at the second keyhole
• only made keyhole on one side, as I find keyholes on both sides bulky when scarf is worn
• instead of keyhole on one side, I did k2 tog across row to last stitch, k last stitch, then did k1p1 ribbing for same number of rows as I did for keyhole
• to increase on the next row, k1, then kfb in each remaining stitch across before beginning garter stitch