Graham,
Your 'sitters' seem to be quite happy at being photographed - which makes a difference, too. (I particularly like the quizzical look on the woman on the left in the top shot.)
Three lights: I dislike too many lights with people images - outdoors I sometimes used reflectors, but almost never flash - didn't marry very well with Nikon's top bodies and only the FM/FM2 variety went up to a 1/250 synch. if memory serves. I think my F and F2 were maxed out at a sixtieth! On indoor locations it was usually a brolly on the subject and another flash on the background if I thought it helped in contrasting person with b/ground. But mostly this was black/white photography. In studio shots it was brolly on subject, perhaps a direct flash behind the subject to rimlight, and another flash onto the background roll to kill off the person's shadow. But usually two was the most, and often just the brolly on the person and forget the white roll - let it go grey.
All depended on what they were wearing, really, and contrasting it with the background. How wonderful Photoshop would have been!
Rob