P is for... Palmer, Professor

Professor Alec Palmer was a scientist who became obsessed with a legendary ghost - or ghast - which haunted Caliburn House in Northern England. It appeared as a white, screaming entity, and had been seen by several witnesses over the centuries. It had even been captured frequently on film.

Palmer, who had once worked for the Special Operations Executive during WWII, bought the property in order to study the phenomena full-time. In 1974, he had as a guest a woman named Emma Grayling who had psychic abilities. He wished to use her in experiments to try and establish contact with the ghast.

The Doctor and Clara Oswald visited Caliburn House at this time and encountered the spectre themselves. Intrigued, the Doctor decided to use the TARDIS to visit the location throughout the whole of Earth's history, taking photographs at each stop, and he found that it appeared every time. He was therefore able to tell Palmer that this was no supernatural entity but a product of some scientific phenomena. Not only that, but there were two separate visitations in the House.

It transpired that a woman time-traveller named Hila had become trapped in a pocket universe which was rapidly collapsing. With her was a misshapen alien creature.

The fracture in time linked this dimension with Caliburn House and it was glimpses of Hila which people were capturing. The mate of the alien creature had come through the fracture. 

The Doctor was able to rescue Hila and the other creature. Palmer then discovered the reason why the fracture should be centred on his home: Hila was a future descendent of Emma and he. They both had feelings for each other but he had found them difficult to express due to his obsession with the ghast.

He also harboured guilt about the people who he had sent on dangerous missions during the war, many of whom had never returned.

Played by: Dougray Scott. Appearances: Hide (2013).

• One of Scott's first big TV roles was as the main character's older brother in The Crow Road, a BBC adaptation of the Iain Banks novel. This featured Peter Capaldi as Uncle Rory.
• He was later the villain of the second Mission: Impossible movie.
• Palmer was originally going to be Professor Bernard Quatermass, previously only hinted at as being a real figure in the Doctor Who universe.
• Quatermass would have been a much older man in 1974. Unfortunately, by casting the 36 year old Scott, it means that Palmer would have been a child during WWII, so highly unlikely to be a senior figure with the SOE sending people to their deaths, even if a child prodigy...