lounge and the Thunderbird 5 control room. To accommodate the simultaneous filming of the TV series and Thunderbirds Are Go, APF purchased two more buildings on the Slough Trading Estate and converted them into new stages. As personnel and studio space were divided between the two productions, filming of the TV series progressed at half the previous speed, with B crew shooting one episode a month. Filming on Thunderbirds Are Go was completed by June, allowing A crew to resume work on the series to shoot what would prove to be its penultimate episode, "Ricochet". Production of Thunderbirds ended in August 1966 with the completion of the sixth episode of Series Two. In February that year, it had been reported that Grade had been unable to sell the series in the United States due to disagreements over timeslots. In July, he cancelled Thunderbirds after failing in his second attempt to secure an American buyer. The three major US networks of the time—NBC, CBS and ABC—had all bid for the series, with Grade repeatedly increasing the price. When NBC withdrew its offer, the other two immediately followed. By the time of its cancellation, Thunderbirds had become widely popular in the UK and was being distributed extensively overseas. Grade, however, believed that without the financial boost of an American network sale, a full second series would fail to recover its production costs. He therefore asked Anderson to devise a new concept that he hoped would stand a greater chance of winning over the profitable US market. This became Captain Scarlet and the Mysterons. Casting and characters Dialogue recording sessions were supervised by the Andersons and Reg Hill, with Sylvia Anderson in charge of casting. Dialogue was recorded once per month at a rate of two scripts per session. Supporting parts were not assigned, but negotiated by the cast among themselves. Two recordings would be made at each session: one to be converted into electronic pulses for the puppet filming, the other to be added to the soundtrack during post-production. The tapes were edited at Gate Recording Theatre in Birmingham. In the interest of transatlantic appeal, it was decided that the main characters would be mostly American and therefore actors capable of producing an appropriate accent were used. British, Canadian and Australian actors formed most of the voice cast; the only American involved was stage actor David Holliday, who was noticed in London's