Why do so many companions come from London?

[TommyR01D]

In the Classic Series, we often didn't give much attention to the homes or families of companions. In the revived series they play a much bigger role and we continually return to the "normal" lives of the Doctor's assistants in between adventures.

This makes it all the more striking that so many modern companions come from London. I know London is a rather large place with a very large population but it seems odd that with the whole universe available, the primary companions are all youngish women from the UK, and almost all are from the same city. It's especially odd given that Doctor Who has been made in Wales since 2005 and in the UK nowadays it's seen as deeply politically incorrect to be too London-centric. Nevertheless, the list is quite illuminating:

Primary Companions
Rose Tyler - Powell Estate, London
Martha Jones - London
Donna Noble - Chiswick, London
Amy Pond - Scotland, then Leadworth, then London
Clara Oswald - Blackpool, then London
AsBill - Brixton, London

Secondary Companions
Mickey Smith - London
Jackie Tyler - London
Adam Mitchell - England (unspecified)
Jack Harkness - Boeshane Peninsula, then No Fixed Abode, then Cardiff
Wilfred Mott - Chiswick, London
Rory Williams - Leadworth, then London
Danny Pink - Gloucester, then London

 

[Nerys Myk]

The Doctor needs to stop going there.

 

[The Nth Doctor]

Because it's familiar, I guess.

Damn annoying though. Not only do I want a non-Londoner, I want a non-human and/or a non-contemporary companion. My favorite companions have been alien or non-contemporary, so it's no surprise that out of all of the new series characters, only Jack (who is originally non-contemporary) and Donna (and to a lesser extent, Amy, Rory, and Mickey) are among my favorite companions.

 

[Tallguy]

Because now that the Doctor can fly the TARDIS reliably they can all go home whenever they want. It's changed the whole show IMHO.

 

[The Nth Doctor]

Another change I don't like...

*old man muttering*

 

[The Wormhole]

AsBill - Brixton, London

Has it been established Bill is from London? IIRC, from the production photos I've seen the only indication of her origins is that she's attending university in Bristol.

Which reminds me, it did slightly irritate me that Face the Raven had Rigsy living in London despite the indication he was living in Bristol in Flatline. I know, he could have easily moved, but it only increases to the centralism of London the show has.