Hi Gibster,
According to my source (English Gunmakers, Bailey and Nie), William Jones, father, son, and grandson, were Birmingham makers who marked some of their guns "London". The elder Jones worked at 86 Lichfield St from 1811-1819 and then 2 Newton St. from 1820-1828. He died in April 1828 at age 50. His son, William, carried on the business at Newton St until 1834, then at 23 Lench St. 1834-1852, and then 75 Bath St. from 1853-1880. After 1881, the family business was carried on by William, the grandson, at the same address until 1891. He moved to 25 Whittall St in 1891 and continued in business there until 1900. Apparently, they paid the London Gunmakers' proof house to do some of their barrels.
dave