Dear GeorginaO,
Thank you very much for sending me the link with the description of the attacks of Georg Haag's shops. They were looted despite he was a naturalised British subject and his son fighting in the British Army. The article is a good source and perfectly fits in and augments my research. Meanwhile I have also found out that your great-grandfather was elected treasurer in the Chesterfield Pork Butchers' Association (1895, 1897; Source: Sue Gibbons, German Pork Butchers in Britain, Anglo-German Family History Society Publications, Maidenhead 2001, pp. 26, 27, 30).
Perhaps you can find out more about him in Chesterfield's Town Archive and in local business directories of the time, e.g. the addresses of his shops or also old adverts in the newspaper.
Regards
Histres