At the moment, when the school gets very low scores on the screening test, (and they will) I can't see there being any consequence for the school. All they have to prove is that the strugglers continue to receive support in Y2 until they 'pass'. They've only just had Ofsted and were 'good', although with concerns about KS1 teaching
and attainment.
If the phonics screening test bothered them in any way at the moment, there would be plans to purchase phonic schemes and the teaching of phonics would be upped to a daily session. Neither of theses things have happened. They don't care.
If the results were made public, they would be far more bothered about their status in a public table as a good leafy lane school. As far as I can see, they don't give a stuff atm. However, publishing the results would bring its own problems.
So, Dilys and Bonsoir, what is it about the screening check in its current format that would make you think the school will change? Because I can't see that it will make any difference whatsoever, for the reasons SoundsWrite outline in his OP.