I am Gerrit Kan from Holland ( Netherlands) and I am the owner of the Union in your picture collection. The picture is made during a show of Dutch (Netherlands) products in Amsterdam. organisd by a magazine. I own a small museum with bicycles,mopeds and motorbikes and a lot of small items.
The bike was made in 1939 and has a Viliers 125cc engine made in England.
In 1939 if a bike is lighter than 60 kilos you only had to pay road tax, if is is heaver you paid extra tax, so bikes like this have been very popular in Holland and a lot of factories built light motorbikes. After the war Union stopped building motorbikes and only made bicycles and mopeds.
The NV Union Rijwiel Fabriek in Den Hulst built autocycles using Victoria engines. Later they built the Achilles Capri under license and mopeds using Sachs engines.
Photo kindly provided by Theo Jonkhart