Timeslip in Colour S1 E6 The Wrong End of Time

Simon, whose mother has died recently, has been taken on holiday in 1970 by the Skinner family - father Frank (Derek Benfield), mother Jean (Iris Russell) and daughter Liz - to the village of St Oswald. Frank had served at the (now abandoned) naval research base in St Oswald during World War II, where he had suffered amnesia. This has left him with no recollection of what happened during his time there. A local girl, Sarah, disappears through an invisible time barrier, witnessed by a local man, but nobody believes him when he tells the story in the pub where the Skinners are staying; but his story attracts a man called Charles Traynor (Denis Quilley), who arrives in the village and reveals that he was Skinner's commanding officer at the base during the war. Traynor had ordered Skinner to destroy the apparatus which the scientists at the base were working on, and he is eager to learn from Skinner if he succeeded in the task. This is because a German expeditionary team attacked and took over the base for a short time in 1940. The German commander, Gottfried (Sandor Elès), is now a prominent scientist, kidnapped and forced to work on the other side of the Iron Curtain, and Traynor is concerned that if the research work done at the base had fallen into his hands, it could be used against the West. While out playing near the ruins of the naval base, Liz and Simon encounter the Time Barrier for the first time. They are transported back to 1940, to the very day the Germans took over the base. There they encounter both Traynor, who is commander of the base, and Liz's father, a young naval recruit (played by John Alkin). A link is maintained to the present via Liz's mother, who is able to communicate telepathically with her daughter. After crossing the Time Barrier Liz and Simon encounter the teenage girl Sarah who fell through the barrier and help her return to the present day. When the Germans arrive, Liz and Simon are initially captured, but then escape and succeed in helping young Frank Skinner carry out Traynor's orders to destroy the secret apparatus - a prototype laser weapon - before the Germans can seize it. They escape back through the Time Barrier, but instead of returning to St Oswald in their time of 1970, they find themselves in an icy wilderness.
During their experience in 1940, Liz is shot yet the bullet does not harm her, which seems to confirm Traynor's advice to Liz's parents (in 1970) that the children are not actually in any danger from the time travel because they are only hallucinating about it and the past cannot harm them.