Jet Rocket and the Swing Wings

It's not often that a vintage plastic X-plane toy pops up on the web but this X-15 pictured above turned up on fleabay last week. Nine inches long and made by Cowley, a manufacturer not known to me. As it's an official X-plane toy it's by default related to the SWORD Dyna Soar aka the X-20. The swing-wings also remind me of that other plastic 'X-plane', the diminutive SWORD Scout 2 seen below.

We still know little about the concept behind the Scout 2. Back in 2008 WOTAN identified the likely origin as these swing-wing 'rocket aircraft', which featured in a single black and white photograph in TV21. Scout 2 appears below for comparison.

The caption to the photograph is hard to read so I've typed it out below. Any further information about this mysterious rocket aircraft would be much appreciated!