I have a lot of information on the Neilson family at hand. This is the same family found in Scotland that were into the iron and steel industry as well as locomotives around Glasgow through the 1800's and into the 1900's. One of the members of the family was James Beaumont Neilson who was known as 'Hot-Blast' Neilson from his invention of the hot-blast for iron and later steel smelting.
One of the Neilson daughters married into the Thomson family of shipbuilders on the Clyde and that is my connection. My grandmother was Marion Paterson Neilson's youngest child. The family business of J&G Thomson Shipbuilders of Govan & Clydebank were bought out in the 1890's and became John Brown.
The parents of John Fraser Neilson born 27 July 1884 at 1 Montgomery Drive, Kelvinside, Glasgow were William Nielson born 24 Dec 1844 at Summerlee, Coatbridge and Alexina Gutherie Fraser born 30 Dec 1857 at Brechin in Forfarshire. I am a second cousin, twice removed to John Fraser Neilson.
How are you connected to the Cazalet family?? I have nothing more recent on the family than about WW1 or so.Oh, by the way, I had understood that the children of William Lewis Cazalet that you list were by his first wife Helen Marshall who died in 1911 as he didn't even marry his second wife until 1918.
I have lots more on both the Neilson and Thomson families if you'd like to contact me at my regular email address, I can send you information by email attachment.