Can anyone advise please, if one is looking at hip scores for Labradors parents with a view to deciding on likelihood of puppies having good or bad hips, I understand the calculations regarding Breed Mean Scores and lower the better and ideally even between both scores on each dog, but to determine the BMS does one use the BMS that was in place when the dog had the score taken (so in this case it was scored in 2013) or should one use the BMS in place today?

I'd use the BMS in place today for considering hip scores.  But if a dog is just a couple of points over that, on one parent, I wouldn't over-react. I would also be paying a lot of attention to the Estimated Breeding Values on Mate Select and whether those are in the red or green, when considering hip or elbow scores... I'd pay probably more attention to that than the individual score of the parent dogs.