Person X was born in Berkshire, and has lived in Berkshire for various parts of their life. Whilst Person X is famous, Person X doesn't really seem to have done anything to warrant fame other than to have a famous sibling (Person Y), and to have assisted Person Y during a very notable event, where it could be argued that (at least part of) Person X actually upstaged Person Y.
Person X and Person Y are both famous enough in the UK that if they were referred to by just their first names, almost everybody would know who they were.
AB/CD/EFGH = Person X's date of birth
JK/LM/NOPQ = Person Y's date of birth
R = Number of letters in Person X's commonly abbreviated first name
Cache can be found at N51 21.RMB W000 51.QGD