Worked fine after a couple of minor tweaks

Initially I tried this and couldn’t get the maps to display at all. After picking up a few clues on the OS Openmaps forums, I made a couple of simple tweaks to the code in the plugins folder and fixed it. Apparently, if your wordpress site is https – something that’s becoming more popular – then you’ll probably need to make these tweaks. I have written the instructions in the Support section.