British Nationality could be obtained through your birth, or through the birth of any one of your parents or grandparents, in Jordan. This arises because of Britain's relationship with Jordan and Britain's 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 Jordan that have been passed over the years.
STATUS OF JORDAN
As “TransJordan”, Jordan was originally a part of Palestine. Therefore, up until 28.09.1923, the Crown exercised extra-territorial jurisdiction in the country.
Between 29.09.1923 and 17.06.1946, Jordan was a British Mandated Territory.
From 18.06.1946 and up to the present day, Jordan was a foreign country.
For more information on how British Nationality could be gained through your birth (or a parent's birth) in a British Mandated Territory coupled with a UK-born grandparent, watch this short video by Philip Gamble: