but noted that the set only appeared satisfactory due to alteration in shots by Martin, who had placed the TARDIS in a different spot than planned to avoid showing too much of the set. The jungle set from the fifth episode, designed by Wood, used hanging gauzes to provide depth; ivy, sea fern, and twelve bags of peat were used to dress the set. The floor was painted to appear marshy, aided by the actors' performances, but was flat to allow movement of the Dalek props; the paint had to be removed immediately after production. The prop used by Ian against the Fungoids was a tube with a battery-operated bulb at the end. The rooftop set in the final episode was raised off the studio floor, with a blown-up aerial shot of a jungle laid atop. The crew decided not to destroy the model of the Mechonoid city as it burns in case of a later Mechonoid story; instead, a crossfading effect between shots of the model and stock footage of a volcanic eruption was used. Following the recording of the last episode, Martin wrote to Cusick and Wood to thank them for their work on the serial, crediting them for significantly contributing to any praise that the story would receive. Casting and characters The Chase marks the final appearance of series regulars William Russell and Jacqueline Hill as Ian Chesterton and Barbara Wright, respectively. Their departure was announced on 1 April 1965; Russell explained that the creativity had gone and he wanted to reenter comedy and theatre performances, and Hill said that "It has been great fun, but you can't go on forever". They made their decisions independently, and gave extended notice to Lambert. Hartnell was greatly upset by their decision, becoming the sole original actor remaining on the series, and both he and Lambert tried to persuade them to stay; Hartnell said to Russell, "What's the matter with you? You've got three kids, you've got a job and we're having a great time – what more do you want?". Lambert eventually decided that Ian and Barbara would depart simultaneously, in a mildly romantic manner. Hartnell's final lines after their departure were left ambiguous in the script, stating in parentheses that he would say "Something about always fussing and bothering and getting in the way"; in the recording, Hartnell said the brief line "Silly old fusspots". Hartnell was not