Captain Richard Haliwell was the captain of the space ship Cygnus, one of the British Imperial Fleet heading to the Moon in 1878. He was selected for the mission as part of his promotion as the British navy wanted a captain with no strong attachments to Earth who had demonstrated an ability to think outside the box.
He kept a diary of the adventure that happened around him, including the discovery of a mysterious park on the dark side of the Moon. During the expedition, Haliwell and his men encountered the Fifth Doctor and Turlough, who had discovered a future version of Halliwell's diary in the TARDIS Time safe and arrived on the Moon to fulfil its "prediction" of their role. After meeting the Doctor, Haliwell seemed to fall in with him quickly and allowed the Time Lord to help with their investigation of the moon. They were chased by all manner of creatures until they were saved by Captain Sinclair.
Haliwell was slightly attracted to the Professor's daughter, Emily Boyes-Dennison. They got along well after they had been captured by the Warden in the Citadel, forced to stay together and endure its tests due to the Warden's inability to speak English.
Held prisoner in the warden's vast palace, Haliwell and Emily were tested using experiments such as a running corridor, where they would escape an electrified wall, or being made to swim for a prolonged time, Haliwell eventually deducing that they were being tested as possible prey. In a later test, they were forced to choose weapons for a fight. Haliwell chose a large cutlass and a small axe. In an artificial forest they met teeth and sword with all manner of creatures. Their last enemy was a Hydra, which he managed to defeat using his cutlass and blinding the creature's three eyes. He treated Emily's wounds using an alien solution. He continued to write his experiences in his diary.
They were then confronted by two robotic hunters, one of which Halliwell managed to slash to bits with his sword, although the other was crushed underneath a saucer which Turlough had flown. Emily was keen to fly one of them to his dismay and worry, but he gave in.
He led the crew to the lift off from the Moon's surface, and proposed to Emily during their return flight, but Emily asked him to consider if he would support her beliefs in equal rights for the genders rather than believing in her as an individual example. After the attack by the Vrall was narrowly averted by the Doctor and Turlough, Halliwell immediately proposed to Emily again after she was discovered alive, telling her that, while he did not yet share her views, he was willing to learn more from her. When Victoria ordered all records and relics of the Imperial Space Fleet dismantled, Halliwell entrusted the Doctor with his diary, knowing that the Doctor would be discreet and wanting some record of their incredible journey to remain. (PROSE: Imperial Moon)