Stalla is not a common surname in England. I have found the following Stallas listed in censuses from 1841-71. I have tried to find parish records for the birthplaces of these people but without success so far. IGI has not helped me either. If anyone has parish records for these places, I’d appreciate a look for the birth of Robert H. Stalla.
1841 Census
James Stalla, St. Mary Islington East, Middlesex, 12, est. birth 1829, Middlesex
William Stalla, Wimbish, Essex, 13, est. birth 1828, Essex
1851 Census
William Stalla, Lambeth, Surrey, 51, est. birth 1800, Ireland
1861 Census
John Stalla, Sheffield, Yorkshire, 41, est. birth 1820, Falbdon, Northumberland
1871 Census
Charles Wallace Stalla, Penrith, Cumberland, 64, est. birth 1807, Penrith, Cumberland
George Stalla, Greenwich, Kent, 58, est. birth 1813, Chatham, Kent