Hi Paul—no one else has contributed here—so I thought I'd have another stab
Your piece is definitely not an M104 tumbler—like you say yourself M104 has no optic ribbing and has a less pronounced waist.
The catalogue link I posted above was for a vase from the 1960 catalogue, available in three sizes. Like I said, I can't make out the pattern no. or sizes from the scan, but the photograph shows a vase of the same shape as your piece, with a pronounced waist and vertical optic ribbing.
Also check pattern #9464 from the 1957 catalogue (but appears only available in 13" in the '57 catalogue).
From experience I know that there is a world of difference between 'looking like this', and actually being the real thing.
I agree; but if I felt I didn't have something to contribute then I wouldn't have bothered.
My problem is that whenever I see 'amber/gold' with a ground pontil I automatically think of wfrs.
or Stuart, or Webb or a good few others! The important thing, IMHO, is the way
the pontil mark has been ground out & polished in combination with a whole host of other factors.