Stuart Hyde, along with Dr Ruth Ingram, was the Master's assistant in creating TOMTIT. Kronos rapidly aged him when he "fed" on Stuart's timeline after his escape, but he was later cured by the Third Doctor. (TV: The Time Monster)

Hyde went on to become a university lecturer in 2003, with one of his students being the Doctor's future companion Melanie Bush. Depressed at his belief that the Master had been primarily responsible for the creation of TOMTIT rather than himself, Hyde later passed on his knowledge of TOMTIT to his student, Paul Kairos, who created the TITAN Array to analyse the higher dimensions directly. When the Master attempted to steal TITAN, the Sixth Doctor assisted Stuart and Paul in tracking it down, a temporal trap that the Master had created as part of his schemes causing Stuart to regress back to his mid-twenties. A meeting with a now-sane Kronos confirmed that Stuart had been uniquely responsible for TOMTIT — as the Doctor had told him, the Master lacked the human ingenuity needed to perfect the calculations — Kronos having arranged for Stuart's regression in age to give him a second chance at life without Kronos's mistakes. (PROSE: The Quantum Archangel)

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