I don't know about you, but calling our capital the Capital looks distinctly odd.
You'd normally capitalise a proper noun, such as the name of a place or building, but not the noun category to which it belongs. London deserves its capital letter because it's our capital city, but capitalising Capital sounds presumptuous, even snobbish, because our capital is one of many.
And yet this must be a deliberate move on behalf of TfL. Their press office checks what it publishes exceptionally carefully, with never a spelling mistake to be seen, meeting proofing standards that must be the envy of other public bodies. If they're now saying London is the Capital, they mean it.
A couple of years ago, in one of their press releases, they suddenly started calling the New Bus For London a New Routemaster. This turned out to be the first phase of a total rebrand, applied relentlessly across all media, so thorough that even the metal plaques on the bus's rear staircase switched from "New Bus For London 2013" to "New Routemaster 2014".
What can we expect in the next phase of capitalised Capital rollout? Consistent usage in all of TfL's press releases, yes, but are there plans to spread this over-pompous wording elsewhere? The Capital Overground? The New Bus for the Capital? Visit the Capital? The Tower of the Capital? Might TfL even transform into TfC - Transport for the Capital?
No, probably not. But something recently inspired TfL to rewrite their style guide, whatever that reason might be, and however ridiculous the outcome might look. Our capital is not the Capital, surely, whatever this whim of capitalisation might suggest.