BOAC, Pitch attitude is not an indication of aircraft performance. I welcome you to come flying with me and I will demonstrate the pitch attitudes to which you refer and not only will I be able to do so in level flight, but also with an indicated rate of descent.
I am crediting you with being a Professional Aviator, so it with great discomfort that I ask you to return to Excercise 19 of the PPL syllabus. The attitude/attitude indicator is merely an indication of just that, not aircraft performance.