A big thank you to everyone who replied to my query on stoneware kiln furniture.  
 
On recent form, clearly there are far more historical archaeologists interested in kiln furniture than there are historical archaeologists interested in helping to develop metric equivalents of traditional analytical methods as a teaching aid (but those African burial ground kiln furniture images used a ruler that's in both inches and centimetres - it can be done, you know).
 
More seriously, I am genuinely grateful for the help.  Sincere apologies for not contacting everyone individually, but I really was swamped with helpful replies, so I hope you'll all forgive me for sending the one single group reply.
 
Thanks,
 
Alasdair