♠ A J 10 6 2
♥ A 6 2
♦ Q J
♣ 10 8 7
North opens 1♠.
South has a powerhouse, plenty strong enough to jump-shift. But playing 2/1 it's usually simpler when you make the 2/1 response, and save your jumping for later - if at all. So South bids just 2♥, knowing North must keep the bidding open.
North knows South has at least 5 ♥s, so his first priority is to agree on the trump suit. He bids 3♥.
South now makes the slam try. She knows North has at least three trumps, and all she wants to find out is how many Aces/Kings North holds. So she bids Blackwood and North confesses to two Aces.
Still hoping for the Grand, South bids 5NT. Oops, North doesn't have any kings so South settles for a small slam.
This is a good slam, cold if West makes any opening lead other than a ♣. With a ♣ lead, South will have to pull trumps and play to discard a loser on the ♠10.
♠ K 5
♥ K Q 9 8 5 4 3
♦ A 4
♣ A 4