The writing looks like Eric Dobson's to me.
Concave, round polished pontil marks were introduced by the Boffos, and were only done during the Harris/Boffo period - they were work intensive. Most of the 11" carafes I've seen have round polished pontil marks - I suspect they may mostly be early. I also suspect that carafes this shape tend towards an early period - much later ones (they were produced for a long period) have very pronounced shoulders - they're more bell-shaped.
However, I have seen big bell shaped ones in Amethyst..........
Exact knowledge about these sorts of things is scant - most of my suspicions about what was made when, and how scarce things are, comes from studying pieces I've seen - so all my evidence only comes from the bits I've encountered in the secondary market - and that is NOT a comprehensive representation of the production.