A Victorian mystery

A day of unremitting rain and mist, suitable for a bit of Victorian mystery. I came across a rather splendid window at St Michael and All Angels Church in Kerry/Ceri in Montgomeryshire. The east window depicts the crucifixion. It looks like a classic Charles Kempe window. Indeed, it is described as being by Kempe in the church guide. The window is dated to 1871. This is the first problem. The date seems unlikely to me since the window is dedicated to Charlotte Jones who died that very year. More mysterious is that, in the very bottom righthand corner of the window is a tiny black running greyhound. I've only seen this mark once before. It is the maker's mark of Herbert Bryans, not that of Charles Kempe. But, Bryans didn't set up his own studio until 1897 so how could the window be from 1871. Bryans worked for Kempe for ten years and his designs closely echo those of Kempe. This is a Victorian whodunnit. Could it be a Kempe window with subsequent alterations (a new dedication panel) by Bryans?

I needed a long lens to photograph the tiny greyhound so will return one day to do that. In the meantime my blip is a detail from another of the lower panels with its 'Flos Florum' inscription - 'Flower of Flowers' - Chaucer's description of Mary.