@dash_ca3: good point. It depends on the age, but if you had twins in their terrible twos, it could prove very difficult to keep them both strapped in.
@ others: I am starting to repeat myself. I have put forward my arguments; does anybody have a good counter-argument?
@TT: last year I priced up a trip and ended up going with BA. It was about ten quid more which was taken care of by availing myself of a G'n'T. We had one suitcase, IIRC. (I've just checked my usual route and BA is currently cheaper than EZY out of LGW with no suitcase!)
So, once more: there is nothing in the loco service model that says they can't get small children safely seated before the majority of passengers board. Other locos do it.
@ExXB: children do not "need" to be boarded early. But they do need to be sat by their parents. The best way of accomplishing this with the minimum of inconvenience to others is to get them on early. Or have designated rows. Or even assigned seating.
As I've said, people who have paid for PB should *welcome* this - it gives them a chance to avoid the small children.