I had a pair of those back in the day. They certainly made more expensive speakers than the Severns, Castle Howard comes to mind. I suspect that if you google Castle Speakers you should see a few up for sale.
I can't compare them to the Severn but my mate used to own a pair of Harlechs and I seem to remember they sounded lovely in isolation. My mate did say they required decent amplification to shine, he used a Linn power amp and pre amp to drive his pair. He later upgraded to some Linn floor standers that cost way more money but I was always a fan of his castle speakers, just a shame I couldn't afford to buy them off him at the time.
Slightly odd design I seem to remember, the grill was assymetrical with the front cones mounted off centre and there was also a speaker cone on the top of the cabinet which was an interesting idea for a more spacious sound stage (so they said)