How many historians' opinions do I need to get an A*?

Your history exam is less about collecting the opinions of other historians and listing them, rather more about your ability to construct an argument whilst analysing alternative opinions. You should read around the topic areas you need to cover in each module, know what perhaps 2 or 3 major historians think of the relevant period or event. Having 10 historians listed in your essay won't earn you marks if you don't constructively explain, challenge or compliment the stance with evidence and analysis. Using the opinions of others to craft your argument, by displaying these scruntinous skills, is the real aim of your essay and is what your examiner will reward you for the most.