I have obtained a photo of the members of the Tonbridge police force in 1900 (attached) and I'd like to identify the Superintendent as he was my great-great-grandfather, Robert James Styles. I've tried to research the differences in uniform to help identify him, but I lack confidence in the identification because I am not sure how these traditions may have changed over the last 100 years or so.

I'm assuming that the majority of personnel in the photo wearing helmets with no stripes on their arms are constables and those with helmets and stripes are sergeants. Which leaves two members in the centre of the photograph, both with relatively simple uniforms (no buttons or belts for example). I cannot begin to work out the rank of the gentleman 2nd row from bottom, 4th from the left. And I assume the gentleman 2nd row from the bottom, 5th from the left is the Superintendent.

Can someone with more knowledge than myself please advise on the ranks of the two unidentified men?

Many thanks in advance,
Neville