I think it was originally in Hanway Street. Just north of Oxford Street near Tottenham Court road Station. That was my downfall really as my Uni was just 10 minutes walk away.
Somewhat spookily I just read the article that showed those pictures and someone mentions going to Hanway Street & buying African Dub Chapter III in 1978 as it had just come out. They were playing it in the shop & I asked what it was. I recognised Dennis Brown's voice but not the dubby version that was being played
The guy behind the counter said he'd only tell me if I agreed to buy one - was never sure how serious he was, lol. Anyway, I said OK and walked away with a copy 'fresh off the boat' I think it was my first purchase there
Of course, what I didn't realise was everything they played on the shop's sound system sounded bloody marvellous - cost me a small fortune that place!