Mr Southall (and or the Southall family) had the Greyhound for a considerable time. It was obviously a successful tavern, probably down to Mr Southall's skill in using advertising and in taking up opportunities to bring in business. Some examples :
1849 The first meeting of the Apollo Glee and Friendly Society, which aimed to promote classical music and culture and to provide funds for medical help, was held at Mr Southall's house, the Greyhound
1851 A harmonic society was established at Mr J Southall's using the new and elegant concert hall at the Greyhound
1864 John Southall announced £100, £50 and £25 pound society at the Greyhound
1864 was selling 'Barm' (by product of ale for bread-making) if someone would take it regularly
1866 Jno Southall advertised his superior tapped cask ale
1867 John Southall advertised his recently tapped pale ale casks which used the malt of William King Malster of New Town Aston
1869 John Southall's ale used Digbeth water and malt from William King of New Town Aston
1873 John Southall was still proprietor
Source all extracts: British Newspaper Archive