Abstract: A tension detector has a flexible strap (350) having its end stitched into a loop (352) that wraps round a central shaft (354). A U-shaped one-piece coil spring has two coiled end portions (356) and (358) wrapped round the shaft (354). The end portions (356) and (358) are inter-connected by a central stirrup (360). A tether strap (316) has a loop (362) sewn into its end which engages round the stirrup (360). The ends of the shaft (354) are journalled in side walls of a housing (366). Each side wall has an inwardly direct abutment projection (368). The upper surface of the housing (366) includes a window (370) through which an arcuate indicator (372) is visible. The indicator (372) has side legs (374) and (376) that are slidably mounted on the stirrup (360). When the strap (316) is relaxed, the left hand end of the arcuate indicator (372) is visible through the window (370). When the strap (316) is tightened, the arcuate indicator (372) pivots to the position shown in FIG.