Fastener combination including a groove and a nut

A fastener combination comprising:

• a mounting body to which an element is to be fastened;
• the mounting body having an elongate receiving groove defining a receptacle therein, the groove having a mouth located at a surface of the mounting body and a receptacle portion behind the mouth, the receptacle portion being wider than the mouth so as to define two shoulders each on a respective side of the mouth;
• a nut member having female threaded hole therein, the nut member being shaped and arranged to be located in the receiving groove, the nut member having a width greater than the width of the mouth so as to define front bearing surfaces on each side of the hole for engaging the shoulders, the female threaded hole being located between the bearing surfaces and arranged in an operating position with the hole at right angles to the mouth;
• and a fastener member having a male thread thereon shaped and arranged to pass through the mouth and to engage the female threaded hole in the nut member so as to pull the bearing surfaces of the nut member against the shoulders;
• the nut member being shaped such that its width in a direction longitudinal of the female threaded hole is less than the width of the mouth so that the nut member can be inserted into the receiving groove through the mouth with the hole at right angles to the operating position and can be rotated in the receptacle portion to turn the hole to the operating position;
• wherein the nut member includes a pair of elements each element being arranged along or adjacent a respective side edge of the nut member and arranged to engage with a respective element along a respective shoulder so as to resist outward movement of the shoulders.