Yeah,I finally found it!
Of course,on reflection,there is a lot more than the circuit,such as the description,PCB layout,etc.,so yes,I can see where they would claim copyright.
Electronics mags in the past were considerably more "laid back" about such stuff,as they were in many cases on the other side of the fence.
In the very early days of Radio & Electronics,manufacturers tried to enforce their Intellectual Property over things like valve (tube) design,& applications etc,but it pretty much fell apart at the seams,as the magazines of the time persisted in publishing data & circuits for Hobbyist use.