The entire first two seasons are currently believed to no longer exist, although poor-quality off-air soundtrack recordings survive for the second season stories "Seven Serpents, Sulphur and Salt", "Nightmare Gas" and "The Eye of Ra" parts 2, 3 and 4. The third season survives in its entirety. Additionally, around nine minutes of a studio recording session for "Sisters Deadly" from this final run was discovered at the end of a tape
Bob Monkhouse had purchased from Thames Television to record over in his personal TV archive.
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