According to Sowerby's archives, this is their pattern No. 1351 - it appears in the Thistlewood's Sowerby CD catalogue - Pattern Book XI of 1885, page 13 - accompanied by a diamond lozenge, although the Registration details are too small to read. Unfortunately, this piece is without any marks and looking in Cottle, he omits pattern 1351 (and the corresponding Rd. No.), thus making it difficult to find out the exact date this candlestick was first registered.
Raymond Slack shows an Opal Vitro-Porcelain example like this one - he also reproduces a supplementary page from the Potter Gazette dated 1st November 1879, showing the same design in Queen's Patent Ivory Ware. So the design appears to have been registered either during 1879, or possibly earlier.
Vitro-Porcelain was introduced in 1877, and I'm only guessing, but would imagine that Opal was first, followed by the other colours - including the reactive Ivory Ware. This might suggest that pattern 1351 could have been registered as early as 1877 or 1878, at least in Opal first, prior to being made in Ivory Ware, and might even have been the first candlestck design in Vitro-Porcelain - but that's only my opinion.

According to the Pottery Gazette, a number of Sowerby's candlestick designs (including this one) were still being manufactured into the C20,
although this is the first that I've been aware of seeing, so maybe they fell victim to progress in the way of electricity and were binned, or suffered unduly from breakages. I don't get the impression they've survived in droves. The top separated branches must have given a few problems in pressing, possibly.
Height is 8.75" - (about 225 mm) - sorry it looks a tad dirty, I forgot to wash it.
I'm sure some of the pressed glass people will know the Rd. No. for this design, and I'd be interested to know the date, and thanks for looking

Ref. 'Sowerby's Ellison Glass Works - Glen & Stephen Thistlewood VOL. Three. CD Data.
'English Pressed Glass 1830 - 1900' Raymond Slack.
'SOWERBY - GATESHEAD GLASS' - Tyne and Wear Museums Services Publication - Simon Cottle.