Lets not let facts get in the way shall we. I'm assuming the 45% pay rise you are on about was the Edmund Davis report? The one started and agreed upon by the Labour party, and only implemented by the Tories because they had come into power after the 'old' labour party Home Secretary Meryn Rees had agreed to implement it but was then ouit of power.
It seems the fact that police involved in major incidents amending/altering their statements was common practice and common knowledge at the time. Lord Justice Taylor certainly knew about it. Jack Straw ordered an Inquiry into this practice when it was first mentioned and that didn't find anything wrong in this process of statement gathering at major incidents. The way it was described is this. Immediately after the incident a policeman writes down his notes in freehand on a statement form. Days later the statement is typed up, but he could then be asked to add anything else he may have remembered or seen on that day. He could also be asked or even prompted, quite lawfully, if he had seen a particular thing. If he did he could add that info to the typed statement as well. I believe this was pounced upon by some lawyers and press as being an altered statement, ie the hand written one is different from the typed one. Nowadays the officer would be asked to submit an extra statement, but in them days that was the practice.
Being instructed to alter a statement, is not the same as being prompted for review.