Radio Luxembourg:
http://en.wikipedia.org/wiki/Dan_Dare#Radio_Luxembourg_serial
The New Adventures of Dan Dare, Pilot of the Future aired five times a week on Radio Luxembourg for five years from 2 July 1951. Dan's voice was Noel Johnson, who also played Dick Barton on BBC radio.[6] Each episode started with the command "Spaceships Away!". The 15-minute show was sponsored by Horlicks and on 3 March 1952, the 106th episode of Dan Dare was heard that Monday night with different episodes on Tuesday, Wednesday, Thursday and Friday at 7:15pm. Although the dramatisation was recorded on wax discs for broadcast, the original discs were lost or destroyed.[7] Until recently no copies had ever been recovered but in late 2011 two episodes were found as part of the Lost Shows Appeal, orchestrated by missing episode hunter Charles Norton. The recovered shows were "Under Sentence of Death" (episode 76), aired 21 January 1952, and The Lost World On Mars (episode 53), aired 19 March 1953.[8]
If I remember rightly, 'Journey into Space' was on a Monday at 19:30 on Light Programme.