As a full time working, IRSE licensed, signal engineer the shape and colouring of a distant signal arm is always the same, fixed or not. That is yellow with a black band and fish-tailed (after 1923; prior to that they were red). The shape of course is a visual identifier to differentiate it from a home (stop) signal. The rear face has always been white with a black band.
The signal in the photo has an unfortunate feature in that if the bolt fixing the arm to the post should become loose, the arm will potentially drop to a clear position - a 'wrong side' failure as it is unsafe. All lower quadrant signals had a large heavy spectacle casting that would return the arm to danger if any part of the mechanism failed - this one does not. Of course there could be a stop to prevent the arm drooping on the back of the arm that cannot be seen in the photo. I hope so, especially if the rest of the signals on the line are lower quadrant.
The last time I had anything to do with a mechanical distant was at Radyr, for the Radyr - Pontypridd resignalling when one was installed underneath the Up starter and motor worked from the new solid state interlocking. Shame we recovered it on a later stage of the job as I think it was unique even then and nothing like it has been done since.
Keep banging the rocks together