Abstract: A clinching mechanism has an anvil composed of first (1), second (2) and third (3) plates arranged in a spaced apart stack with the second plate (2) positioned between the other two. The plates (1, 2, 3) are mounted on a housing (43) so as to be slidable relative thereto and the second plate is also connected to the first and third plates (1, 3) so as to be slidably movable relative to said first and third plates between a first aligned position in which at least one edge of the first, second and third plates (1, 2, 3) are aligned to form and anvil face and a second retracted position in which the second plate (2) is retracted from the anvil face. With the second plate in its aligned position, a staple to be clinched in received with its two legs (72) on either side of the second plate (2), the second plate operating to guide the legs (72) into engagement with associated clinching device (7, 8, 17, 18) positioned between the first and second, and the second and third plates.