Under the current voting system, do you need a majority of votes to be elected MP?

That’s the wrong question to ask.  Why?  Because it’s ambiguous.  The word majority has two different senses.  If you look in an American dictionary, it will tell you a majority of votes is a number or percentage equaling more than half of a total.  But if you look in an English dictionary (English meaning from England) a majority means getting the greater number of votes, specifically more votes than the one that comes in second. It does not necessarily mean more than 50% of the total.

The word “majority” even in the context of elections means different things to different people.  To avoid this, use the term “absolute majority” to refer to a majority that is greater than 50% of the votes cast, and “relative majority” or “plurality” to refer to getting more votes than other candidates or options, but not necessarily more then 50%.

With ranked ballots, a relative majority is not enough to be elected MP, an absolute majority of over 50% is required.