Batleys went into 'administration' (bankruptcy protection) a month or so ago and is now in the process of reworking their business model. They've been renamed (No longer "N Batley") and are still selling stock tartans. I spoke to them just 5 minutes ago about something I had recently received.

When a mill runs out of fabric, they typically put it on the list to be re-woven in a few months time.

Please note that some of the mills mentioned above weave MORE than just tartan... some weave solid wool or pinstripes or different solid materials (acrylic, PV, wool blends, etc)