Well done to Amateur Casual for guessing the answer ... these three designs were previewed by the public in 1870 ... here's a press cutting:
LAMPS ON THE THAMES EMBANKMENT
Those who have lately visited the Thames Embankment may have observed some lamps which have been placed between Hungerford and Waterloo Bridges. Three designs are submitted for inspection and approval, in order that the details and the decorations may, in their appropriateness and excellence, do justice to the grander features of the undertaking. The first, by Vulliamy, is of classic character in the stem, with two dolphins supporting or ornamenting the base. The second, prepared by the Board of Works, is in a purely classic style. The third, by Mr. Timothy Butler, represents two boys climbing a column, and the upper boy receiving a lighted torch from the boy beneath. Two overflowing cornucopias form the base of this composition. The idea is suggestive of the transmission of scientific truth and its results in the blessing of abundance for mankind. The designs have considerable merit. Neither seems unfitted for its position of dignity, yet each might bear reconsideration and improvement before any great number are executed. In Vulliamy's, objections might be taken to the position of the dolphins, which look as if they had slid from the glass dome above. In the Board of Works' design the lion legs, issuing from the columnar stem, strikes us as being far from happy. Something distinctly masonic or architectural might be preferred. In Mr. Butler's design, the stem is certainly disproportionately large for the mere support of the boys and glass globe, and a bolder curve might be given to each cornucopia. Allowing for these defects, the design is admirable. It is full of the sense of energy and enterprise, and, moreover, it has the rare merit of being equally effective when beheld from the river or from the embankment.
The Standard, March 21, 1870
Despite the Standard's approval, it was, of course, the 'cornucopia and boys' design which was never introduced, presumably turned down by the Metropolitan Board of Works. Vulliamy's work graces the central London portion, whilst the 'lion foot' version can be found, I think, in Chelsea.
No, I was wrong ... they kept one example of the cornucopia design, to mark the Chelsea Embankment ... or, so it seems, looking via flikr