On another note, I had a go at making a step by step photo guide...let me know what you think of the tutorial!
The measurements I've given allow for a 2cm overlap of lace and elastic on each side to create a headband that is 1cm smaller than the measured head width. If the lace you choose doesn't fray as easily then a smaller seam would be fine, so just adjust as needed.
I hope you all have a lovely, lazy Sunday. After Church I'm planning a day of crafting and rugby (watching not playing - come on England!)...hopefully I'll be able to share my crafting ventures with you later this week.