A girls’ prep school founded with the help of Queen Victoria and Florence Nightingale is closing after more than 150 years and has blamed increased costs caused by government policy.

Royal High School in Bath, whose alumnae include Dame Mary Berry, 90, traces its origins to 1864 as a school for the daughters of army officers. Victoria, one of its original patrons, provided a donation to help establish it in 1865. The first lady superintendent was recommended by Florence Nightingale. In 1998 it merged with Bath High School, which was founded in 1875 and is where Berry attended as a schoolgirl.

The former Royal School campus became the senior school, while the former Bath High School site served as the junior school. Other alumnae from the schools include Jennie Formby, general secretary of the Labour Party under Jeremy Corbyn, Bunny Guinness, the BBC Radio 4’s Gardener’s Question Time panellist, and Helen Rollason, the former BBC sports presenter.

Today, Royal High Bath has a nursery and prep school for girls up to year 6, and a senior school for girls in year 7 up to sixth form. Fees at the prep school are about £16,000 a year including VAT.

In a letter to parents, Heidi-Jayne Boyes, head of Royal High Bath, said it had been decided to close the prep school, including provision for pupils in nursery up to year 4, at the end of the summer term. They will move girls in year 5 and 6 to the senior school.

Boyes blamed a series of government decisions, including “increasing costs with the introduction of VAT on school fees, removal of business rates relief and an increase in employer national insurance contributions”. She added: “Over time, our cost base has risen faster than pupil numbers, coupled with a decline in birth rates nationally, which means market dynamics are rapidly changing. To put the school in the best position possible to adapt to these new market conditions, moving to one site and starting from year 5 will allow us to reduce overheads and invest in areas that will have the greatest positive impact.”

Royal High Bath is part of the Girls’ Day School Trust, a group of 24 all-girls schools and two academies. A parent told The Times the closure was “sad but perhaps not surprising given the extra financial pressures independent schools are facing”.

The prep school and nursery, which have around 130 pupils, moved from the senior school site to a nearby Victorian mansion, Cranwell House, in 2014.