Some casual drain spotting revealed this fragment of industrial history on a Shipley side street.
Lorenzo William Crosta, mechanical engineer, was born on Nottingham in 1862, and later a Director of Ames Crosta Sanitary Engineering Co. Among his patented inventions (May 22nd, 1894) was a double-trap surface water gully, of which this may be an example.
Detective work made easy by Grace's Guide, and Google Patents.
In other news, it seems I may have broken a toe; it's gone a nice shade of black. We'll see how it looks and feels in the morning.