The content may or may not have been harder back in the O level days but you were at the mercy of what the school provided - no internet, no access to past papers (even for a previous spec), no exam spec, no revision guide books to buy from Amazon (no Amazon), no one to ask except equally confuddled class mates, no YouTube videos. I ended up going to an evening class to help with one of my A levels as it was being taught so badly in school - the majority of my class was there.