The latch should look like this, once it has been rebated.

Now we need to mark the spindle hole and so remove the latch and then hold it alongside and mark the position of the spindle using a pencil.

Drill the hole slightly bigger then the size of the spindle. Take your time with this hole and again ensure that the drill is kept square to the door. When the drill bit starts to exit the other side, stop drilling and then finish off the hole by drilling from the other side.

Clean out the hole for the tubular latch and then insert it, ensuring that it is the correct way around. Fix the latch with the screws provided.

Now insert the spindle through the door and the tubular latch. On some doors the supplied spindle is too long and so it may require shortening with a hack saw.

Place the handle onto the spindle and ensure that the handle is straight and then mark the screw holes using a pencil.

Drill a small pilot hole for the screws.

Fasten the handle to the doors using a suitable screwdriver. Ensure that the driver is a good fit, because if you slip off you might scratch the new handles.