The only other shops I remember from the early 70's are John Alvey Turner in New Oxford Street where I used to buy their own brand of all steel strings, much to the dissaproval of Ivor who said I should use La Bella bronze strings, and Macari's Musical Exchange in Charing Cross road where we bought second hand PA for Imperial College Folk Club where I was developing my folk skills when not at the Troubadour.
By the way, David Elliott and I played matching Otwins in the group Matrix, complete with Yagdish on tabla and Anne Shepherd on vocals, and there is a photo somewhere; must put it on my website. The Otwins were both modified to have Grover machine heads.
Denmark Street is now an easy walk from my office so Hank's acoustic shop gets a few regular visits.