Kilgraston uses the philosophy of the Society of the Sacred Heart, to make faith relevant while teaching girls to live together as friends and family and as part of a global community.
The school has just opened a 25-metre indoor pool to boost its sports programme, but Farmer insists that the biggest investment is in people, with high staffing levels keeping class sizes at about 15 pupils.
"The key is that you can still treat them as individuals," he says. "It is the benefit of a lack of distraction from the boys. We have no problem motivating the girls. This lends itself to a more relaxed environment."
He continues: "We spend a huge amount of time out of the school environment, and develop service on the outside. For example, we took some upper sixth girls into a prison because our chaplain also works there."
"We also try to bring in interesting people. We had a day for Darfur and invited a refugee to come into the school – it was incredibly moving.Teenagers are so impressionable, so if you can get them interested at that age, it tends to stick with them."
Kilgraston plans to continue developing its hi-tech classrooms and improving sports facilities, but Farmer says he also hopes to recruit more specialised staff.
The school's location gives Kilgraston a quiet setting, but it is certainly is not cut off from the world. It has strong links with the all-male Merchiston Castle School in Edinburgh and international links with pupils from around the globe.
Farmer says: "We believe in producing strong people with a sense of morals, a sense of right and wrong, particularly in terms of social justice. It is about building a community, that looks after each other."