In a new school tradition, BHS alumni around the world will also raise a glass at 6.30pm in a toast to their school, which began on September 17, 1894 from two rooms of a rented house on Reid Street.

Pictures of the toasts will be collected by the school in a collage celebrating the BHS legacy.

“I am honoured to work with the some of the most talented, hard-working teaching professionals and the best behaved, focused and most enthusiastic students, who love to learn,” Ms Parker said. “We have a legacy of excellence of which we are very proud and all of us will continue to build on this tradition for the next 120 years and beyond.”

Parents joined students and staff for a picnic as all the school’s pupils formed the number 120 on the main field.

The school opened under headteacher Matilda Tothill from the UK’s leading girls school, Cheltenham Ladies College. She arrived on the Island just eight days before school began.

According to BHS director of advancement Jennifer Burland Adams, when the benefactors of the school first began discussing the need for a school for girls, it was said that its only assets were courage, determination and the students who began their educational journey with a tuition fee of three guineas per term.

From three teachers and 51 students to 85 teachers and 630 students, BHS has pledged to put the long term needs of its student first.

Its 19th century principles of “academic excellence, independent and creative thinking, communication skills and a healthy, balanced life” remain in place, Ms Burland Adams said.

“BHS strives to develop students that are resourceful, reflective, compassionate and open-minded as these qualities will enable students of the 21st century to tackle challenges that have yet to be discovered and jobs that have yet to be invented.”

BHS remains all-girls from years one through 11. Its International Baccalaureate Programme, the Island’s first, commenced in 2000 and is coeducational.

Although many schools will only enter their top students, 91 percent of BHS IB2 students took the full diploma in 2014, with 97 percent passing.

The top BHS students have been in the leading percentile worldwide in years. This year also saw BHS students taking A* and A grades for the IGCSE and GCSE exams at more than three times the UK average.

Today’s celebrations were joined by those of four students whose birthdays coincided with the school’s anniversary.