[JMT1985]

Agreed, though I do think they’ve rather tied themselves in knots if that’s the case - any current day episodes where London is in any kind of danger will need to address why an incarnation of the Doctor (who has his own TARDIS and a best friend so brilliant that Unit want her on their staff) who lives just down the road isn’t bothering to help out with the threat…

I know he’s meant to be resting, but in universe that’s a rather very flimsy excuse if people are dying.

When we watch the last scene with Tennant's doctor with Donna's family and she says to him he doesn't have to stay, and he replies we will see. So we all know the doctor would get bored, he actually got bored already by taking Rose to Mars on a trip. So this can easily explain his absence when London or the UK or indeed the world is in danger.