A system comprising: a cover , the cover being a substantially rigid cover and configured to close off an opening to a void having a side wall , and the cover defining a pair of opposed sides , being an operatively top side and an opposed underside ; and a locking assembly for the cover , the locking assembly comprising: a mounting arrangement mounted to the underside of the cover ; a link pivotally connected to the mounting arrangement , the link defining a first end and a second, free end ; a locking member carried by the second, free end of the link , the locking member being configured to frictionally engage with the side wall of the void in a locking position, in use, wherein such frictional engagement of the locking member with the side wall of the void in the locking position, in use, locks the cover ; an actuating member connected to the link and accessible via the operatively top side of the cover , the actuating member being operable to displace the link relative to the mounting arrangement to cause the locking member to frictionally disengage from the side wall of the void to a disengaged position, characterized in that the actuating member is at least pivotally connected to the link . a cover , the cover being a substantially rigid cover and configured to close off an opening to a void having a side wall , and the cover defining a pair of opposed sides , being an operatively top side and an opposed underside ; and a locking assembly for the cover , the locking assembly comprising: a mounting arrangement mounted to the underside of the cover ; a link pivotally connected to the mounting arrangement , the link defining a first end and a second, free end ; a locking member carried by the second, free end of the link , the locking member being configured to frictionally engage with the side wall of the void in a locking position, in use, wherein such frictional engagement of the locking member with the side wall of the void in the locking position, in use, locks the cover ; an actuating member connected to the link and accessible via the operatively top side of the cover , the actuating member being operable to displace the link relative to the mounting arrangement to cause the locking member to frictionally disengage from the side wall of the void to a disengaged position, characterized in that the actuating member is at least pivotally connected to the link . a mounting arrangement mounted to the underside of the cover ; a link pivotally connected to the mounting arrangement , the link defining a first end and a second, free end ; a locking member carried by the second, free end of the link , the locking member being configured to frictionally engage with the side wall of the void in a locking position, in use, wherein such frictional engagement of the locking member with the side wall of the void in the locking position, in use, locks the cover ; an actuating member connected to the link and accessible via the operatively top side of the cover , the actuating member being operable to displace the link relative to the mounting arrangement to cause the locking member to frictionally disengage from the side wall of the void to a disengaged position, characterized in that the actuating member is at least pivotally connected to the link . <EOS>