Garstang applied for the position of physician's clerk at MRI in 1840. This was probably Thomas Blacklidge (or Blacklegde) Garstang of Bolton, who qualified LSA and MRCS in 1839 and was later honorary surgeon at Bolton Infirmary.
However, there are a number of other Garstangs practising in the area at the time, including James Garstang of Clitheroe who qualified in 1827, Walter Garstang of Saddleworth who qualified in 1847 and Walter Garstang of Blackburn who qualified in 1859.