I'm curious to know how common this die flaw is on the 1817 shilling. I've seen it described as very rare, rare... and yet they seem to be fairly common. Keen to get others views on this.
Fairly common. It would help if it was a genuine R instead of a B - but it isn't. It's just a filled section on the bottom loop which is a natural consequence of use over time. The same applies to anything with a missing section of a letter. Filled dies are not really varieties IMO, whereas an R for a B would be.
Sorry about the heavy toning, but it's the best I have to hand. Missing base to B of BRITT, and a second non-variety with unbarred H in HONI in the Garter legend.
Interesting, PCGS have described it as a flaw... but am inclined to agree with you. It's not like the errors you see on William III.
PCGS have slavishly followed what has been written in Coins of England for the past 15 years instead of confirming for themselves what is going on. A flaw is a crack in the die, or a piece fallen off it. Die fill is natural wear and tear from accumulated metal dust produced when coins are struck.
Which is interesting as ESC notes "a broken B" but doesn't give it a separate catalogue number unlike the unbarred H etc. It's a pity Coincraft stopped making its standard catalogue. I hasten to add I don't collect errors, was more just general interest.
It might be a bit of both as I can't recall seeing anything really close to a full B. There are examples with more or less of the loop missing as the right hand side of the gap extends on later pieces to produce a tail closer to an R which doesn't curve back. So could be a broken B with the gap exacerbated by die fill over time. I had taken it to be fill due to the variable nature of the gap and the fact the bottom bar of the B is narrower than the top, but can see how both could apply. On the coin I posted earlier, there is a trace of a line at the missing section which could apply to either situation. FWIW, this is a full B on an 1817 shilling. As you can see, it's marginally narrower at the bottom, and what is not clear from the image, is in slightly lower relief too which would support die fill.
Excellent. These RRITANNIARs have always seemed a bit contrived as rarities for the reasons you've pointed out. I do confess to having an 1868 3d....