Coro St Shock! Horror!

TVNZ isn’t commenting on whether it will screen Coronation Street in HD following the soap’s shock rescheduling to 5.30pm weekdays.

In a press release issued this morning, TVNZ said it was switching Coro St to an earlier slot to accommodate the final stages of MasterChef Australia, which will screen 7.30 weeknights from October 19.

“The schedule change for MasterChef Australia, together with our unique coverage of the Rugby World Cup and the 2011 general election during the months of October and November, will require a change to the scheduling of a number of primetime shows, including Coronation Street,” the head of TV One and TV2, Jeff Latch, said.

He then tried to soften the blow for Weatherfield fans, who can sign the petition here, by pointing out the soap would screen for an extra half-hour each week and in a weekend omnibus.

This suspiciously sounds like code for TVNZ dumping a primetime staple it no longer knows how to maximise, fobbing off fans by saying they’ll get a better deal, and using Coro St’s much lower ratings at 5.30 to justify keeping it in that slot.

Asked if Coro St would revert to 7.30 after the RWC and the election, a publicist told ScreenScribe.tv: “We haven’t decided yet. We want to wait to see how this works out before we make a call.”

You don’t need to read Blanche’s tealeaves to know that screening two hours earlier, three weeks into daylight saving time, the cobblestones drama viewership will be crippled.

Last night’s episode, for instance, drew 7.5% of 25-54 year-olds, TV One’s target audience, whereas the 5pm edition of MasterChef Australia rated only 3.1%.

Sure, interest will grow in MasterChef Australia as the finals loom but Coro St’s ratings also spike when a juicy storyline is unfolding – and there are plenty of those pending, from a lesbian shock to a hostage siege at Underworld (expect both to be edited for the new slot).

Indeed, now would be the time to promote Coro St to the hilt: put some muscle into its marketing, bring some stars down from the UK, run a catch-up marathon over summer …

Hopes of seeing Coro St in HD would appear to be fading with this news, too.

We’re nearing the point where it switched to HD in the UK but TVNZ isn’t commenting on when, or even if, it will screen here in HD.

To save money, TVNZ largely transmits HD content only in peak hour, unless it’s a re-run of a primetime series or a show that bombs.

So don’t expect it to spend more on Coro St at 5.30 than it already is – which probably is at least 10 times higher for the slot than what it would typically budget.

That’s yet another surprise about this announcement: Coro St is the driver of TVNZ’s costly ITV output deal.

A year or two ago, it had to considerably up the ante to renew the deal amid ITV concerns over the broadcaster’s treatment of its flagship drama and when it looked as if Prime/Sky might make a bid. (The Bill and EastEnders failed to fire on Prime but Coro St has considerably more kudos and appeal in this market, and with competent programming and promotion, would provide the channel with the evening anchor it lacks.)

While ITV will be unhappy with TVNZ’s latest sleight-of-scheduling hand, the deal is secure for the next few years, which means TV One can risk sidelining Coro St without fear of a rival poaching it – and if it does do badly, then its legacy will be tarnished when renewal rolls around.