Is this an HMV 163?

[richardh]

Oh yes, you're right. You know I've never noticed that before. Now I look at mine I can see that the 5a has a kind of swirly pattern and the 5b inward pointing triangles around the outer part of the diaphragm. And to think I thought I had sharp eyes and I hadn't spotted than in the years I've had both!

RJ