Because you demanded more Skater Morris! (No, you didn't, but let's just pretend you did...) Here is a sketchbook series of cartoons I did quite awhile ago which strangely hadn't made it to this blog yet, with the exception of the very first one.
Edward Burne-Jones, William Morris' best friend, notoriously sketched cartoons of Morris having "mishaps" for as long as they knew each other. It stands to reason that Topsy was aware of Ned's poking fun at him and tolerated it. Morris was a jolly fellow, after all.
The original idea of "William Morris On a Skateboard" came from Kirsty Walker's husband, Duncan, making a comment about Morris-patterned skateboards.
Which led to... well, this.
Some examples of Ned exploiting Topsy for his own amusement: