Well thats an interesting one, nothing very common I suspect.
Front lower mounted magneto and a front brake can only make it mid to later 1920s,
and what looks to be either both pushrods in a single tube, or maybe even ohc make it one of a very select field.
Which I can't quite put a name to at this stage, although it looks familiar.
Calthorpe ?
Certainly the engine could be in the same family, although the details are not entirely a good match ?
We will see if it jumps out at someone...