Abstract: A ferrule assembly comprises a ferrule mounted in an opening of a ferrule back body. The ferrule assembly is mounted at an end of an optical fibre extending through the ferrule along an axial direction. The ferrule assembly is passed through a tubular section and then through a biasing member. The back body is then inserted into an opening of a back body holder and attached to the back body holder. The back body holder prevents the ferrule assembly from passing back through the biasing member. The insertion comprises moving the ferrule assembly relative to the back body holder in the axial direction. During the relative movement, an orientation of the back body relative to the back body holder, determined by a guide element of the back body, is maintained. The tubular section may for example be a duct as narrow as 3 mm.