SIDRAT

A Space and Inter-time Dimensional Robot All-purpose Transporter, more commonly abbreviated as SIDRAT or sidrat (pronounced "sigh-drat"), was a type of space-time vessel used by the War Lords during their War Games and built with the assistance of the War Chief, a renegade Time Lord. (PROSE: Doctor Who and the War Games)

Like most TARDISes, SIDRATs were larger on the inside than the outside, the dimensions of their interiors could be changed at will and be operated by remote control, but just like TARDISes of the Doctor's day, this was at the cost of the machine's lifespan. According to Jamie McCrimmon, they were green in colour.

From the outside they resembled featureless rectangular boxes. The War Lords employed them both to abduct human soldiers for the war games, and also to travel back and forth from the game area to their base.

The supply of SIDRATs to the War Lords was the War Chief's primary contribution to their plan. The War Lords were dependent on the War Chief for the secrets of space-time travel. His importance was reflected in his rank: second only to the War Lord himself. To force his compliance, the War Chief trapped the Second Doctor within a SIDRAT and shrank its inner dimensions until the Doctor and Jamie were nearly crushed. Later the Doctor confronted the War Chief with a revelation: a timeship with a malleable interior and remote control capabilities was inherently unstable. The War Chief's SIDRATs would never last long enough to carry out a galactic conquest. The War Chief admitted he knew of the flaw in the plan and demanded the Doctor's help, promising him half the galaxy after he betrayed his allies, and death at their hands if he refused.

By the time the Doctor and his allies managed to successfully stop the war games, it turned out that all but two of the SIDRATs had ceased functioning, and the remaining ones would not last long enough to transport the thousands of soldiers back to their original time zones. One of the still-functional SIDRATs was subsequently brought to Gallifrey by the War Lord's loyalists in an abortive attempt to rescue their master. (TV: The War Games)

SIDRATs were in use on Gallifrey centuries before the Doctor's time. According to legend, the tyrant brothers Sabjatrik and Rungar drowned their mother in a leaky SIDRAT. (PROSE: Shada)

Behind the scenes

 * SIDRAT is "TARDIS" spelled backwards.
 * In Malcolm Hulke's novelisation of Doctor Who and the War Games, the acronym SIDRAT is spelt in all lowercase, as sidrat.
 * The 2014 comic Space in Dimension Relative and Time can be abbreviated to "SIDRAT."