Data

I expect it's the influence of Australian soap opera

Except Australians (at least in engineering, if not in the soap you watch) most often say "dahta" .

Right, I'm off to read Desiderayta.

That's what pinchaque said, Ray. British dahta, to the extent it exists, may have been due to Australian influence.

Oh, did he?
Oh well, nothing like getting your retaliation in first.

Most of England.... Day-ta.
North East of England.... Dayt-aah.

OK--what's the Australian soap opera connection?

The UK seems to screen a few of our soap operas, nutrax. I'm guessing it's a reference to the UK's use of the term being influenced by this?

How would a soap opera influence pronunciation of data, of all things?

I can't imagine a scene like
"Oh, JIm, we can't keep meeting like this!"
"Don't worry, Alice. Data show that women with my wife's illness only live an average of two years after first diagnosis."

I'm not entirely sure that comment was meant to be taken seriously.

Old age pensioner - NZ - Dahta, Strahta.

I say datta, stratta, apparattus...