I concur these occur from Malawi, & perhaps were made there under either British or Indian supervision.
There are many others of related style, but lesser quality, Ive just found on a English dealers for sale website.
Obviously I cant link to or post them here, due to forum rules.
But if anyone would like the photos of several others including some possibly of more primitive style, Then just send me an email at
spiraltwista@aol.com & Ill forward the photos. {Put Yao in the email title, so they don't go to spam..}
spiral