I have realised that the last two gigs I saw with left-handed bassists, both players had their instruments (left handed basses) strung with the E string nearest the floor, as if they had learned on a RH bass turned over. Clearly a sample of two is not significant, but is this more common than I might have imagined.
For the record one was Mr Pomeroy (Steve Hackett) and the other Gary Fletcher (The Blues Band).