The dfe need to change the guidance so that the IRP can have more power to reinstate
Giving the IRP more power wouldn't be a simple matter of changing guidance. It would need a change to the law. The Education Act 2011 amended the Education Act 2002 to limit the powers of the IRP. Under that Act an IRP can only uphold the decision, recommend that the governors reconsider or quash the decision and direct the governors to reconsider. The IRP cannot direct the school to withdraw the PE.
This change was in the Conservative manifesto for the 2010 election where they said, "We believe heads are best placed to improve behaviour, which is why we will stop them being overruled by bureaucrats on exclusions". I suspect this was driven by publicity in the press covering cases where IRPs had overruled exclusions apparently unreasonably.
I don't doubt that some IRPs overturned exclusions that should have been upheld, just as some upheld exclusions that should have been overturned. However, I think the system largely worked well and I agree with Admission that the change has not improved matters.
I also agree with Admission that any governing body that chooses to reconfirm a permanent exclusion in the face of a decision by the IPR to quash the decision is taking a big risk. The first judicial review under the new system took place in 2014. The judge in that case was critical of the legislation and the DfE guidance on a number of grounds. He also said that, if the IRP recommended that the governors reconsider it would "be a bold step for the governing body to fail to follow that recommendation". One might infer from this that it would be an even bolder step for a governing body to reaffirm its original decision if it is quashed by the IRP but the judge did not spell that out.
Sadly, the only way the situation will be further clarified is if parents, faced with a school reaffirming its original decision, take the matter to judicial review. However, I agree with Admission that governing bodies need to be extremely careful about the consequences of their decision when considering whether to defy the IRP.