I didn't get any answers so I thought I would post our experiences as they may be useful to others. I emphasise this is just anecdotal from our particular experience. Also, please remember this only applies to households where all other cats are neutered, intact tom cats are well known to be a potential danger to kittens.
As it happened, our pregnant female decided the place she wanted to give birth was on my wife's lap. We moved her into a nesting box when she started, but since this was in the middle of the living room it wasn't possible to keep the other cats out. The younger male (her brother) was interested but we kept him away the others ignored her. Four healthy kittens emerged over the next few hours.
We then moved her and the kittens into my office and shut the door to keep the other cats out overnight. The next day, we kept the other cats out, but the day after we gave them careful, monitored introductions. The other cats were curious, but not hostile, and the mother cat was friendly towards them although she'd politely escort them out if they approached the kittens when she wasn't with them.
Since I work from home, I could monitor them during the day and we left the door open and only shut them in/the other cats out overnight. The mother cat seems much happier when she is not confined, so we've been trying to keep the door open as much as possible during the day. As far as I can tell, there has been no hostility from the other cats towards the kittens and since the mother cat isn't worried I don't think we need to be.
We will continue to keep an eye on things as the kittens grow and for now (they are a week old today) we will keep the door shut overnight.
Since the kittens are 8 weeks old today I thought I'd update: we've had no problems at all. The other young cat (their uncle) plays with the kittens quite often now and is normally appropriately rough with them, occasionally he's a little too rough eliciting a yelp from the kitten but he's never done them any harm. The older cats largely ignore the kittens, although they chase Maggie from time to time.
Keeping the cats having access through the house has also avoided any conflict between the cats beginning, although the older cats have been displaced from their usual spots a bit by the kittens they don't show significant signs of distress and we've had no behavioural problems from the other cats.