Until recently a journalism trainer in the UK could safely berate a trainee for Writing Headlines Where Every Word Began With A Capital.
It is a style of headline writing common in US publications, but non-existent in the UK, where newspapers have traditionally fit into one of two camps: the SHOUTY SHOUTY REDTOPS and the broadsheets who Only make the first letter uppercase unless there’s a proper noun.
(The mid-markets, as might be expected, took the best of both worlds, reserving shouting for the front pages and lower case for the inside pages).
So a journalism trainee who Wrote Like This had likely never paid much attention to newspapers, or only when they appeared in Hollywood films.
Or perhaps they just read Guido Fawkes, who, for whatever reason appears to have followed the Hollywood style of headline writing:

Guido Fawkes’s headlines adhere to the US style
The British headline style has carried through into UK papers’ websites, even while their audience became more US-based.
But today’s announcement that The Guardian will use US spelling when referring to American institutions suggests the start of a change:
“The old argument that “the Guardian is a British newspaper so we use British spellings” has served us well but no longer holds; we remain a British newspaper but one with many more readers outside the UK, especially in the United States.”
And already in the UK British journalists are now writing American-style headlines, for the UK satellites of US brands. Like Huffington Post UK:
So we can no longer assume British journalists will be writing for British publications in a British style.
Of course it may not be long before news websites adopt responsive design which corrects spelling based on the location of whoever is reading it: so an American will read about “the color gray”, and an Australian will read about “the colour grey”.
That’s my little pipe dream. But in the meantime, journalists will just have to do what they’re told.
UPDATE [Nov 21 2014]: The Guardian Style respond:
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It seems to be that, if anything, the trend is moving in the opposite direction. US news media are gradually converting from title case (capitalizing all major words) to sentence case (capitalizing only the first word and proper nouns) for headlines. The Washington Post switched to sentence case in 2009. Since then, the Los Angeles Time, The Boston Globe, the Chicago Tribune, the San Francisco Chronicle, the Houston Chronicle and the Philadelphia Inquirer have all followed suit.
Surely it’s a simple courtesy to refer to an American _institution_ by its preferred spelling (e.g. Lincoln Center) regardless of where you’re publishing? I’m surprised that has not always been the case. I would expect regular vocabulary to conform to the country of publication but not proper nouns.