It is the present layout of the constituencies that is the problem as with FPTP many hard-line constituencies get elected with only very small numbers of votes and a lot of second and third votes are completely wasted.
( It is true that when we are asked to vote using numbered choices rather than putting "X"s in boxes we are going to have to find out more about each candidate. ( This can only be a good thing for democracy ) ).
The general share of the votes has overall - in the FPTP system - been very bad for minority parties as no matter what share of the votes they get they do not get any more seats.
If STV-type PR ever comes in I think you may find that boundary lines between some constituencies will have to be redrawn so that fairness is SEEN to be operating in all of them.
Here is another view of the pro's and con's of the STV system:
http://aceproject.org/ace-en/topics/es/esd/esd02/esd02d/esd02d01