Formed in Liverpool in 1933, the British Interplanetary Society was the first national organisation to draw science fiction fans in the UK together in significant numbers. A London branch was formed in late 1936, and national HQ was transferred from Liverpool to the capital the following year, where it has remained ever since. In 1938, Arthur C. Clarke and William F. Temple, later joined by Maurice K. Hanson, moved into a top floor flat at 88 Grays Inn Road. From here they put out publications for the BIS and the Science Fiction Association and, for a while, that address was the HQ for both national organisations. Indeed, prior to WWII the BIS and SF fandom had a very large overlap in membership and were both part of a greater community of science enthusiasts. With the outbreak of war, both were suspended 'for the duration'. Only the BIS would return. After the war, the BIS and SF fandom went their separate ways. There would always be some overlap, but it would never again match pre-war levels, an observation first made by Arthur C. Clarke during the speech he gave about the BIS at 1948's WHITCON, the first post-war SF convention in the UK.
This page contains links to BIS and rocketry-related material on this website and elsewhere:
There's also this exchange from the pages of THE FANTAST at fanac.org:
There are a couple of books the editor of this site had a hand in that give further insight to the pre-war BIS. The first of these, TEMPLE AT THE BAR collects the fan writing of Bill Temple, SF writer and one-time editor of the BIS BULLETIN. It contains several pieces by him from early BIS publications and is available as a *free* ebook.
The second is THEN: Science Fiction Fandom in the UK (1930-1980) which covers the earliest days of the BIS and contains more on the non-BIS doings of its first members.
Another free ebook worth a look for those interested in the sort of war various members had is HOMEFRONT: Fandom in the UK (1939-1945).
There's also a page on Ken Gatland on this site. This includes a link to a section on the 1944 Eastercon, which he and possibly other BIS members attended.