Hi there,
Literally just found this thread. I'm pretty sure this is late 1970s-80s Mdina, from the Earthtones range produced after Michael left. I'm pretty sure I've seen this shape before, but it isn't common as you correctly say Pip & Andy. I have a catalogue from that period at home in my archive, but I'm not at home right now, so can't check it. So until then, I'll say I'm 95% sure it's Mdina as described.
Hope this helps,
Mark