Actually, Angela, Lattimore mis-read the Henry Greener lozenge, because the (rather indistinct) day identifier is actually 29 (not 23), giving a registration date of 29 July July 1876 – Parcel 6, corresponding to RD 302199. I have 2 reference photos of the mark and, as you say, both have an ‘R’ rather than the usual ‘Rd’, but both marks are also surmounted by Henry Greener's ‘1st lion’ trademark (used between c.1875 and c. 1885).
Lattimore also points out that the design was for the looped border rather than the shape, and although the grape and vine decoration appears on some of the RD 302199 shapes, it does not appear on all of them (see Lattimore's plate 54 on page 84, and my last photo). It is interesting, though, that Henry Greener pieces around this period are often found in opaque white glass (though normally the opacity is quite dense and uniform rather than milky), so it is not impossible that the covered pedestal bowl shown in your opening posts may turn out to be a Henry Greener piece.
Fred.