How do I get him to stop, or hold my hand?

[LaTristesse]

DS is 2, did a runner at the library this morning. Straight out into the car park. I obviously chased him shouting To stop, which he thought was hilarious and just laughed. Thank god there were no cars.
He refuses to hold my hand (we get a tantrum, which when juggling newborn DD and change bag at least isn't so easy to deal with). I've ordered him a wrist strap but I'd like him to either understand that it's dangerous to run away or and that he needs to do what i say. Is he still too small for this? Lots of his friends seem to get it, or at least do as they're told, but this incident is by no means a one-off. Any ideas?

DS (nearly 2) has a little life backpack that he chose himself, and though he's an independent little bugger boy and won't hold hands, he will wear his backpack, especially as putting it on is always a precursor to being allowed out of the buggy/house to go for a walk.

That being said, I absolutely insist on holding his hand when we cross the road, and when we wait at the lights. When we're in the park and he's not using his backpack, he has a choice of walking and behaving himself, or going in the pram.

In case of tantrum, he gets picked up and I clamp his knees firmly (but without hurting him) so he can't kick.

It works. And he is the most appallingly tantrummy child.

You get bolters and non-bolters. I think I've got two bolters! Buggy is probably the best on longish trips, and wrist strap or reins for very short trips.

This is one thing where I am completely over-protective. I have a sensible DS (4.1 now) and I still make him hold my hand in car parks and when crossing roads and will do for the foreseeable future, although I do now trust him to walk and scoot sensibly even by busy roads. I'm scarred by him bolting across a car park aged 2.6 when I had a newborn baby and not enough hands free - 30 seconds earlier or later he would have been flattened, but the car park was miraculously quiet at that moment.

We live on a main road so I have had to be very strict with him - so from about 18months old we have always talked to him about road safety when out and about, about how drivers can be bad drivers as well as good drivers and how it can be hard to see small children, how we have to wait for the green man, walk away from the kerb etc. I also always do what my dad did - put me between child and the road so if he bolts away from me it is more likely to be forwards backwards or into the hedge and give me chance to grab him, rather than straight into the road.

DD is 19mo and already a liability. She is always in the buggy on our busy road and will be for the foreseeable future until I can trust her on quieter streets. I get her to practise holding my hand when crossing quiet streets and if she doesn't then she gets scooped up under my arm and carried across, however much she howls. And we already have started the 'there's the green man' 'be careful of cars' talk too but I doubt she will be even vaguely trustworthy for another couple of years.

It took 2 years for it to sink in with DS and now he is very sensible and has a very good understanding of how unpredictable and dangerous traffic can be. But I don't think I will ever trust him 100% so remain close particularly in car parks (where I think drivers can be much more easily distracted looking for spaces etc.) and on main roads.

I think reins and backpacks work or they don't.

dd1 had a little life backpack and it was great. dd2 used to do this thing where she would go limp as soon as it was on, so it was like trying to drag a very heavy puppet dangling on a string. she was a tantrumming, bolting ever loving nightmare, so she went in the pushchair until she was old enough to get it, and now she does.

Is there a 'reason' you need him to 'help' you, tell you where it's safe to walk, cross road, etc?