I'm not personally aware of any cut celeries with lozenge or Rd. No. (that's not to say there aren't any) - against which is the fact that there are scores of pressed examples which carry Registration details - so this is a rather pessimistic way of saying that the chance of finding a maker for this one is probably frighteningly low.
Almost certainly unrelated, but perhaps worth mentioning as a feature which might possibly help with dating, is the cog wheel/saw tooth foot rim on this one which has a counterpart on a number of pressed pieces from the Derbyshire factory. In 1872 J. J. & T. Derbyshire Registered an entire suite No. 268810, all pieces of which (and there's something like eight separate shapes including a celery) have this design of rim in abundance. In fact when Neil recently had a cut celery (with this style of foot rim) which he believed to be M.W., Derbyshire as a maker was suggested on the basis of the rim alone - although think positive attribution remains unknown.
Not suggesting at all that this one is Derbyshire, but having an identical foot rim might just suggest a date of c. 1870s. Alternatively, this might be red herring, and there might be absolutely no date connection at all. Have a look at the Derbyshire designs and see what you think.