Harry's great great great grandfather Henry Saxon Snell
Henry was an architect. Some of the pages which can be found with a google search for his name include:
Biography from the web-site of McGill University, Canada
We learnt from this page that one of Henry's sons was called Harry Saxon Snell!
Biography from the newsletter of the Royal Society for the Promotion of Health.
See the second page of this PDF file, whose first page has the strange title POOSH, (Professional Organisations in Occupational Safety and Health)! Alternatively browse
this html version of the file