This is the actual document I typed out when planning a third strip

The Outpost Gallifrey Doctor Who Christmas Story

Should be one episode only, but an episode that nonetheless is longer than most single episodes.

Featuring the Third Doctor, Jo Grant and Brigadier Lethbridge - Stewart.

Light hearted, easy going Christmas story, akin to the scene after The One Doctor and Blackadder's Christmas Carol.

So, the basic storyline is thus -

Episode 1 of 2

The aforementioned characters are settling down to a Christmas meal, with the Doctor using his newly created turkey oven in the TARDIS to prepare the traditional Christmas fare. The Brigadier doubts the ability of the machine to produce a perfectly edible turkey, and is proved right when the Doctor emerges, embarrassed, holding the smouldering remains of the bird.
The Doctor then decides to whisk everyone off in the TARDIS to a proper Christmas meal in the court of his good friend, Henry VIII. However, the TARDIS does not land in its intended destination. Rather, it materialises in the middle of an empty living room. Looking around, they realise that they have landed in the middle of the UNIT HQ living room, on the close of Christmas Eve. As they prepare to leave, a figure comes in, and they hide behind the TARDIS , not knowing who the person is…

Episode 2 of 2

The figure places a device in each of their stockings (on the mantelpiece above the fireplace) and then proceeds up the chimney. They realise that the person was the Master, and, upon looking into their stockings, they see he has hid crackers in them, each one containing a small explosive, but enough to do a great deal of damage. The Doctor has an idea, and ushers all into the TARDIS.
Arriving on the roof before the figure has been able to complete his ascent of the chimney, they lasso him with a set of Christmas lights. "Merry Christmas, Master", as the Doctor illuminates his arch enemy.
Later on, as the trio finally settle down to their turkey, the Brig asks where the Master is. The Doctor glances up as the very large Christmas tree, atop of which is the Master, bound and dressed as a fairy.

So, while the final story is no different to this original plan (although there are a few lines added here and there), I had changed it to two episodes, despite originally stating one before I had even finished the plan.