I think The Lodger is the first televised story to be explicitly based on a comic strip; Human Nature / The Family of Blood was based on Paul Cornell’s Seventh Doctor novel Human Nature, and Blink on Steven Moffat’s short story “‘What I Did on My Christmas Holidays’ By Sally Sparrow”. Gareth Roberts borrowed some elements from his comic strip story “A Groatsworth of Wit” for the televised The Shakespeare Code, but tonight’s The Lodger is a much more direct lift from his comic strip story of the same name, originally published in Doctor Who Magazine #368 in 2006.

It is fairly easy to list the elements which are directly transferred from the original to the TV episode.

1. confusion between sonic screwdriver and toothbrush (though originally Mickey uses the former as the latter)
2. Tardis takes off with companion leaving Doctor behind (though originally this appears to be an accident)
3. The Doctor cooks his host a superb omelette (though in the original we only see him promise to do this)
4. The Doctor joins his host’s football team as a last-minute substitute and plays brilliantly (wasn’t it fortunate that Matt Smith wanted to be a professional footballer and played for the youth teams of Northampton Town, Nottingham Forest and Leicester City? though I suppose any decent actor could have made an effort to carry it off; and also a fortunate coincidence that this was shown the evening of England’s debut in the World Cup)
5. The Doctor promises to leave his host alone to entertain a date, but completely spoils it by wandering into the conversation, chatting with the girl and encouraging her to change her career path (though in the original, Mickey’s friend Gina is a one-page character, nowhere near as central as Sophie, and Ten tells Mickey he has ruined the evening deliberately because his [Mickey’s] heart is elsewhere, whereas Eleven is just being gormless)
6. The Doctor’s host finally loses his temper about being continually upstaged
7. The story ends when the Doctor engineers a happy moment between the lovers (though it’s a different girl, ie Rose, rather than the same girl whose earlier date was interrupted)

The key elements of the original story which didn’t make it to the screen are as follows:

1. It’s a story about Ten and Mickey, rather than Eleven and a couple who we have not seen before
2. The Doctor is just crashing at Mickey’s rather than renting
3. The Doctor also beats Mickey at video games and tunes his TV to ten years in the future, and then helps his friends beat the quiz machine in the pub after the foorball match
4. The Doctor casually repels an entire alien invasion fleet in less than half a page as an incidental detail

From this it will be fairly clear that a lot has been added to the original 9-page comic to turn it into a 45-minute TV episode. First off, the central Craig / Sophie dynamic is much more powerful than the original, which essentially gets Rose and Mickey to the point of pressing the “reset” button yet again. Second, the missing Tardis and obligatory alien menace are very directly tied into the Doctor’s choice of lodging; there is a whole extra storey to the TV story (sorry, couldn’t resist it). Third, while Amy doesn’t do much in the TV version, she still does a lot more than Rose who appears only on the last page of the original; and Sophie is one of the key characters on TV, far more so than her original incarnation as Mickey’s date Gina. These are all improvements, and I will be interested to learn how much was Moffat and how much was Roberts; there were a lot of moments in the Craig / Sophie relationship that seemed to me very Moffat-like. I really liked it anyway.