A sheet clamp comprising:a body having first and second sides and an aperture extending between the first and second sides to provide a channel through which a portion of one or more folded sheets may be inserted in use from the first side to the second side；the channel having opposed side walls, a dimension of the channel between the side walls decreasing from the second side to the first side；a clamping block having two block sides dimensioned to be received within the channel with the block sides engaging the side walls of the channel when inserted from the second side of the channel；a retaining member pivotally mounted on the body and moveable between a first position in which the channel is open, permitting the block to be removed from the channel and a second position in which the retaining member covers the channel from the second side preventing removal of the block from the channel.
