Apparently these were
produced in clear - I'd rather overlooked this fact - and Lattimore shows one end of a trough in clear (identical to mine) - this is the only clear example I can find. Otherwise, the books tend to show only Vitro-Porcelain, Queens Ware or Marbled examples.........see Raymond Slack and Sheilagh Murray, although there is a very attractive Blanc-de-Lait example in Simon Cottle.
At first I thought this one might have been a C20 piece, since it's so clean and devoid of water staining, and doesn't have any wear to speak of on the feet - presumably never used - but the sharpness of the moulding and trade mark look very crisp.
Perhaps these clear ones are much rarer - what do people think? thanks for looking, and does anyone please have the other threequarters of my clear trough