Lily-Mae Fisher, who died when a Merlin Mk4 helicopter crashed during routine training in southwest England, was "Britain's only serving female Royal Navy Commando", the navy said.

The 31-year-old passed an arduous training course including a 30-mile (50-kilometre) march to become a green-beret-wearing commando in 2022.

The BBC reported last year that seven women had successfully completed the All Arms Commando Course since 2001, including Fisher, while 17 had attempted it.

The lieutenant was killed on her final flight training assessment and was due to qualify as a helicopter pilot this month.

She died along with two other Royal Navy service personnel.

Fisher had an Instagram account with more than 45,000 followers where she talked about issues faced by women in the military, including dealing with menstruation while in the field.

"She has been an inspiration to countless people, particularly young women, encouraging them to achieve their dreams," the defence ministry said.