A locking member 1 in the form of a collar can provide a strong mechanical joint between a tube 5 and an apertured plate 6. The locking member 1 has an outwardly directed flange 2 and an inwardly directed flange 4 and is accommodated on the end of the tube 5 which is then inserted in the aperture in the plate 6. Axial pressure applied to the end of the tube 5 will result in the deformation of the locking member and the tube end about the plate aperture resulting in a strong mechanical joint being formed between the tube 5 and the plate 6.