All I know is that they were very smart and well tailored but way too expensive for most of us. We got our uniforms from Moss Bros or Alkits. Only senior officers or those with private means could afford Gieves prices. The same went for hats from Bates. Other than No 1 Saville Row they didn’t have “shops”, a gentleman tailor would visit you by appointment in the Mess.
Good luck with your project.
TL