If all the questions are answered correctly and the £1000 is banked, then the person who banked, is the strongest link and the weakest link is always the second person to be asked a question. The reason for this is because IF they had banked (which they hadn't) they would have only banked £20, whereas if anyone else banked, they would have banked over £20.
Notice that the voice-over always says that they are statistically, the weakest link, so it doesn't matter if someone has hesitated, the second person is statistically the weakest link.
How the contestants vote is a different matter.