Looking at the Public Members Tree on Ancestry
George Platnauer - birth c1826 born Russia/Germany - married Julia Silverstone - April 1856 London.
(haven't checked whether this marriage is on Ancestry) - as it would give his residence, he is of course living in Bristol 1861 census, but not at home 1851 census, at 11 Bath Street - which is a later Directory on Ancestry - is where the business was.
Lewis - is on the 1851 census - and a Watch Maker
---
On the 1883 Kelly's Directory of Birmingham
Platnauer Brothers, watch manufacturers, Ludgate Hill
Platnauer George, watch manfr, see Platnauer Brothers
Platnauer Lous, waatch manufacturer, & vice-consul for Portugal, 1 St Paul'[s square. See Platnauer Bros.
Although Julia was born in Brighton (later census) - she is with her family in London 1851 census - so only assume George was working there at some point. - as Mark SILVERSTON, her brother was also born in Prussia.