Because of the close links between the two schools, Sixth Formers are able to benefit from an unrivalled range of some thirty subjects at AS and A Level.  The two schools share a common Sixth Form timetable, with the result that an enormous range of subject combinations are possible.  Students are normally taught at their ‘home’ school, but will have lessons at the other school where necessary in order to keep the range of choice as wide as possible.  In addition, some subjects are taught at only one of the schools – Ancient Greek, Computing, Latin and Russian at Monmouth School, and Business Studies, Information and Communication Technology and Psychology at HMSG, to name some examples.  The two schools therefore work together to produce one of the most varied sets of subject options to be found in any school, with co-education being a feature of many Sixth Form classes.

Co-operation between the two Sixth Forms also extends to the shared use of the two Sixth Form Centres, the joint delivery of Enrichment courses, the provision of visiting lecturers, choirs, orchestras, plays, the Combined Cadet Force, the Christmas Disco and Summer Ball, as well as a range of subject societies and other informal opportunities – many of which are run by the students in conjunction with members of staff.