Hi Diana,
This was one of the subjects we covered, at a Solent Branch meeting, you must have been at sea that week.
You must have picked up on the vibes, I have been practising recently for the summer season of shows, I will show you on Tuesday if you make our meeting.
If not, to answer your question it starts with a five part by three TH, then you break out of the regular rythem of a TH and with some maths weave like a twill.
Ken.