been introduced in The Armageddon Factor, was ditched in Part Four of this story. This was also the first story to use the Quantel DPE 5000 digital image processing system. Filming on the story ran badly over budget. The opening sequence on Brighton beach is John Nathan-Turner's paean to Visconti's celebrated 1971 feature film, Death in Venice. Format changes This was the first Doctor Who story which John Nathan-Turner produced. Nathan-Turner was keen to get away from what he considered the excessive silliness of recent Doctor Who stories, and wanted to increase the series' production values, because he felt that they were poor when compared with glossy American science-fiction series. Among the changes Nathan-Turner instituted was the scaling back of K9's appearances (the unit is out of commission for most of this serial), eventually writing the character out in Warriors' Gate. Nathan-Turner would produce Doctor Who until 1989. In a further attempt to update the image of the series, the original 1963 Delia Derbyshire arrangement of the theme music was replaced by a more contemporary-sounding arrangement by Peter Howell, and a new, '80s-styled neon tubing logo (which was en-vogue at the time) designed by Sid Sutton replaced the diamond logo most associated with the Fourth Doctor. The updated title sequence is most associated with the Fifth Doctor. Tom Baker, Lalla Ward, Barry Letts, and Christopher H. Bidmead all protested John Nathan-Turner's decision to add question-marks to Baker's shirts, arguing that it was gimmicky. Baker in particular was unhappy with it and told Nathan-Turner that it was "annoying, absurd, and ridiculous", while Bidmead later called it "a silly, quite absurd gimmick really". Bidmead, who found working with Tom Baker "difficult to say the very least", supposedly told Baker and Nathan-Turner during recording of The Leisure Hive that exclamation marks would have been more appropriate for Baker's shirts. The Seventh Doctor Sylvester McCoy would later protest his question-mark adorned jumper in similar terms, but the question-mark motif would remain until the end of the classic series in 1989. Baker also disliked his new scarf, requesting that his old multi-coloured one be re-instated, but expressed gratitude to costume designer June Hudson for refusing to adhere to Nathan-Turner's demands to ditch the trademark scarf altogether and managing to find a compromise. The show's stars took exception to many of John Nathan-Turner's other changes as well, with Tom Baker and Lalla Ward criticising the change