In ‘An Unearthly Child’ the Doctor pretends to be distracted to avoid Ian and Barbara’s probing questions. At one point he picks up a picture frame and claims that he hasn’t seen it before.
This is obviously a ruse but what if the picture frame was actually important? What if the Doctor is genuinely perplexed by its appearance in the scrapyard. He never has a chance to investigate it but it could be the starting point for one of your own adventures.
So what is the picture?
A Glimpse Of The Future
The picture could show a future adventure of the Doctor. It could be that it shows Ian and Barbara in the past, making him realise that he has to take them with him. When they insist of barging into the TARDIS he knows what must be done and takes off.
It could be a picture of something sinister in the past, much like how the Doctor follows an image in Van Gogh painting in ‘Vincent and The Doctor’. This could occur at any point in the Doctor’s history. He might have a sense of deja vu only to recognise his surroundings as the scene in the painting from the scrapyard.
It could the painting be a copy of Van Gogh’s picture of the TARDIS exploding, the portrait of Ace seen in the extended cut of ‘Silver Nemesis’ or the painting that the 11th Doctor posed for in ‘The Impossible Astronaut’.
The reason that the Doctor has only just noticed it is because his future timeline is crystallising around him. Now the human teachers are here there is no turning back, no chance to deviate.
What the picture shows him will happen.
The painting could serve as a warning to the Doctor. It could be that someone with access to time travel knew he would be there and sent the picture. While this could be combined with the above, the warning showing something disastrous in his future it could depict something that needs his attention.
This could be ‘Bad Wolf’, a picture of Clara (maybe the one the 11th Doctor paints in ‘Bells of Saint John’) or something similar. The picture could be one that appears to the Doctor across multiple incarnations (maybe the 4th Doctor spots it again in ‘The City of Death’ while rushing through the Louvre.)
Did the Doctor get a good look at it? He complains that it is damp and dirty. It could be that he doesn’t understand that this is a warning at this point. It could be much later that he realises its significance.
This could be a good way to add foreboding to an adventure featuring the Doctor. He might realise what the warning related to and either investigate or go back to the scrapyard to see if he can find the picture to discover any details he missed and work out how it got there.
Rather than being helpful the painting could be a trap for the Doctor. It could promise something or imply that he has to be at a specific time and place only for his enemies to ambush him.
The picture could be quite tantalising. The reason the Doctor never mentions the painting again to the others could be because it reveals something very personal (for example his family).
The 1st Doctor could be quite the schemer. He might wait for the appropriate moment to travel to the place depicted in the painting, concealing his motives. This would follow an early theme of the Doctor getting his travelling companions into trouble because of his own goals.
This requires that the trap setter know the Doctor well enough to know what to put in the painting. If they are time travellers they would also have to be careful that they don’t change anything in their own past. This would make it seem unlikely to be the Daleks as he hadn’t yet met them (from his perspective).
The painting itself could be dangerous. It could be a shape shifting alien that took the form of artwork to avoid being detected. It could be a dimensional prison, absorbing living beings into itself. It could be a mental parasite that replicates by making a viewer wish to copy it endlessly.
The Doctor may have fallen victim to it here and the adverse signs only manifest later. He might have escaped falling prey to the painting only because Ian and Barbara intruded. This means that they unknowingly saved his life.
The painting could claim other victims after the TARDIS crew dematerialised. The Doctor and his companions could return to 1960s London to investigate those who have been preyed upon by the painting and trace it back to this brief encounter. Alternatively a fresh group of PCs could deal with the threat that the Doctor missed.
The painting could have a hidden code intended for the Doctor. Most would dismiss a painting featuring high gallifreyan as abstract art (or any other alien language for that matter) but the Doctor would understand it perfectly.
A Time Lord sympathetic to the Doctor’s cause could leave him a message, warning him that his own people are closing in on him and that it is time to leave. Or it could be a Time Lord hunting him giving him a chance to surrender.
The importance of the message contained in the painting might only become apparent later. It may contain a key phrase that can be used by someone in the future to alert the Doctor to their importance.
The PCs in your campaign could leave the painting as a way to communicate with the Doctor (maybe setting up a meeting with them later). Whether he responds is another matter.
The painting could also contain galactic co-ordinates. Would the Doctor make an effort to go there or would he avoid it? What did the creator of the painting want him to do?
The Painting Belonged To The Original Owner Of The TARDIS
Susan could be clearing out space in the TARDIS (which seems unlikely due to the size of its interior) or just trying to make it their own by removing anything of the previous owners. In fact the whole scrapyard could be cluttered by bric a brack collected by the mysterious owner of the TARDIS.
The painting might have sentimental value or it could be a dangerous relic (much as the The Worshipful and Ancient Law of Gallifrey in ‘Shada’ proved to be much more than just a book).
Leaving the painting in the scrapyard could have unforeseen consequences that the Doctor or other PCs have to deal with. They might find themselves delving into the art world to recover it from various collectors.