British Nationality could be obtained through your birth, or through the birth of any one of your parents or grandparents, in China. This arises because of Britain's relationship with China and its Colonial history.
To determine what form of British Nationality you might have, an analysis of your family's history must be done, and then applying it to the Nationality laws of China (including Hong Kong and WeiHaiWei) that have been passed over the years.
STATUS OF CHINA
From 26.06.1858 until 19.05.1943, the Crown exercised extra-territorial jurisdiction. From this date, it became a foreign country.
WEI HAI WEI