kladdaka the 17 teachers sacked were those removed from the teaching register of the GTCE (is it still called that?). This is like a doctor being struck off. The real number of teachers no longer teaching because of incompetence is, I would imagine far, far more that this.
Not sure what all the fuss is about; the means of moving poor teachers on already exist, but many HTs do not use them because they are afraid of the unions. Well, if they have the evidence, they have nothing to be afraid of.
Handled properly, this should not be problematic. Oh, hang on. Much of this depends on the HT. Over the years I've seen weak teachers bullied and not helped; lazy cronies promoted to VERY high positions, and staff who do not kiss ass edged out of their jobs.
I predict a massive rise in teachers bringing in the union at the first opportunity, instead of later, as usually happens. This will be good if it means proper evidence of incompetence is given, and appropriate help given to those who need to improve. It will, however, be seen as "those unions" protecting poor staff, when they are only ensuring due process.
BTW, I have been a union rep sitting in with staff who are being helped to be better, and have instigating first stages of competency myself.