The last (8th) strand end will tuck up through the adjacent bight completing a full round. Note that it passes through a bight which does not have a strand end exiting as that bight previously held the first strand end
Start third round, again in a counterclockwise direction, passing the first strand end up through the bight from which the next strand end exits . . .
Starting the fourth round.
Do as many rounds as you feel appropriate for the knot. Shown here is after six rounds.
Pull the strand ends gently to work up the knot, being careful to keep the strands in order inside the knot.
Draw up the knot over the end of the previous sinnet, covering the permanent seizing
The finished Matthew Walker should leave the 8 strands protruding toward what will be the bottom of the bell pull.