Doesn't include Internment Camps?
There were 9 of these in WW2 Isle of Man.
My grandmother's father died 1942 aged 86. He had been born in mainland Europe in 1854 in the British territory of the Kingdom of Hanover..
Otto Von BISMARCK was the president and foreign minister of Prussia. He dominated European affairs after he masterminded the unification of Germany by waging war on all the little states and principalities. America recognised this enlarged country of "Prussia", which meant Britain eventually followed suit and the Kingdom of Hanover when invaded by the Prussian army. The locals were not treated very well. Stories of Hanovarian families escaping clandestinely during darkness, or for example by water skiing along canals and other means became known much later, because to leave a Germanic state in those days meant you needed permission in triplicate for every border that needed to be crossed.
The only people who had free access across Europe were musicians and my grandfather had an uncle who toured with a band of musicians. So, aged six he was touring the European music circuit, playing a violin in a Hanovarian band. The group arrived in England when he was 10 years one day old. Aged 15 he met Lucy, aged 20, he married Lucy and they had six children. Their four sons were called up to serve in the RAMC during WWI and their father wasn't sent to a camp but he did have to report to the local police station every day. during WWI and later in WWII.. In those days a child and a wife took the nationality of their father/husband, thus his wife also became an "Alien" and she too had to report to the local police station.
All the Germans who lived in Britain were treated suspiciously, many had opened their own butcher shops; and, as stated already, many were sent to the interment camps.
Early 1980s my son-in-law was sent on a two year work contract near Munich, Germany. I visited one summer and visited the local park, which was void of all other humans, until a little old man from a nearby house walked along side the iron railings until he reached the gate and then headed straight for me. In broken English he apologised for WWII blaming the Prussians who, he explained, were always waging war on people.