According to the documentary accompanying the Network DVD release, the concept for this show originally envisioned it as a programme aimed at youngsters in the mold of other children orientated sci-fi such as The Tomorrow People or Doctor Who. However the documentary goes on to state that this idea soon dissipated when the two stars (McCallum and Lumley) were signed, the production costs subsequently spiralled and made it impractical to keep this as part of childrens TV programming. The programme was then written for an older (i.e. teenage) audience in mind and moved up the schedules from a childrens tv slot to an early evening slot (most ITV networks screened it around 7pm). Despite the big name casting and sci-fi elements the show was not a massive hit not because of perceived lack of quality but because the haphazard way it was produced with the stars availability together for filming being restricted due to other commitments. This meant that the show could never really get a strong foothold in tv programming due to the irregular way the stories were becoming available for transmission. Without a regular production schedule the shows ended up showing at different times and dates all across the ITV network and as such production eventually fizzled out with some ITV networks not showing the final stories until 2 years after they had been filmed.