H.M.S. TARDIS was the seventh illustrated short story in the 1968 Doctor Who Annual. It featured the Second Doctor, Ben and Polly. It was a rare instance of the Doctor actively trying to change something about the known history of Earth.
The Doctor, Ben and Polly land on the HMS Victory during the Battle of Trafalgar. In the lull immediately before the fight with the Redoubtable, they must prove to Flag Captain Hardy they are not spies or deserters. The Doctor proposes to his companions that they try to do a bit more than that. He tells Polly that he aims to change history, but neither Ben nor she believe he is capable of that. He tries to give Nelson specific advice to avert his death, but, in the end, Nelson dies, anyway. Still, Ben seems to have changed history a tiny bit, by encouraging Nelson to send a message to the whole British fleet: "England expects that every man this day will do his duty."
- The Bucentaure, under Villeneuve, the Redoubtable, and the HMS Royal Sovereign, under Collingwood, are mentioned.
- A battle at the Nile occurred, during which the Indefatigable was lost.
- Like many early Doctor Who print stories, both comic and prose, the Doctor is referred to as "Doctor Who" or "Dr. Who". The word "doctor" is but once even seen as a proper noun here when used on its own to refer to the character.
- As with other stories in the 1968 annual, the second Doctor refers to Ben and Polly as "my children", or, individually, "my child", "my girl", or "my boy". Uncharacteristic of the Troughton Doctor, this seems to be a hold-over from the Hartnell interpretation; there was simply too little time between when Troughton took over and this annual had to go to print for the annual's editors to understand Troughton's approach to the role.
- As in other illustrated stories throughout the annual, the Doctor is shown here wearing his stovepipe hat.
- The Doctor's stance on changing history seems unusual in the light of The Aztecs, and many historical stories thereafter. Here the Doctor is actively trying to ensure that Nelson will live into old age, instead of being killed in the Battle of Trafalgar. In fact, it's his companions who have to reign in his enthusiasm, which is decidedly jingoistic. He tries to enlist Ben's aid by saying it's "for the good of England" that they save Nelson. In the end, though, it's possible to interpret the Doctor's activities as scientific more than patriotic. "I had a feeling all through that it couldn't be that easy," he says, almost indicating that he was experimenting with changing history just to see if it could be done. Another interpretation is that since the Doctor has only recently regenerated, he is not in a stable mind when thinking about the rules of time travel, and explains why he acts out of character.
- This is one of the few stories in which Ben plays a dominant role, and in which his naval background is significant to the plot. Ben is in his element here, certainly more than in any televised story, and probably more than in any other story in any medium.
- This is the first of two times the Second Doctor has direct contact with Lord Admiral Horatio Nelson. Though this occasion is at the very beginning of the second Doctor's life, the next instance, in PROSE: World Game, came after his trial in TV: The War Games.
- The Doctor would later be present for the Battle of Trafalgar again during his both eleventh (COMIC: Rough Waters) and twelfth incarnations. (COMIC: Ghosts of the Seas)