Mike, really sorry the net is not what you are after.
I checked my net last night, I have the "locking nut" slightly tight which means that I can step on the net and extend the handle and it does not rotate. Right enough though, if you undo the nut completely, the handle does rotate, which I had not noticed.
My handle remains a fixed length 95% of the time however, which is probably why I missed it.
Might I suggest a trip to Aberdeen to your local tackle shop as they have a good range of nets, including Sharpes, McLean, and a few others. At least you can try them there