I don't let my scent hound pup pull, but I do let him dictate everything on sniffy walks which means if he starts to pull, unless it's something he shouldn't be doing due danger, I move with him.

Just enough tension to remind him he's with me, but not so much tension he isn't doing what he wants.

At first he would really protest about being asked to walk on - and I was worried this approach would reinforce him thinking he rules the roost

But actually I've found the complete opposite, it's like 20-30 seconds of sniffing and he moves on with a simple whistle or "walk on". Repeat this for say, the first half of the walk and then he walks like a superstar for the rest of the time.