What a brilliant thread. I am with Keith on the 'age' and confidence issue. However I do know that I would have got it all in pre. If you bust you can do the 'yeah,ran in to aces' whilst waiting for the sandwich to arrive. But then what do I know. No need to answer that.
The whole hand would play out differently against you though Ian.
If Keith's been aggro which I'm assuming is the case then Sam's actions are very different compared to when he's up against yourself who probably wouldn't be opening quite so often.
Your UTG opening range is vastly different to Keith's which in turn affects Sam's BB 3/5 bet range. The only way it ends up in the middle against you is if he's got the same hand or AA. Vs Keith he can get it in with worse and also have a bluffing range thrown in to boot.
This isn't intended as a knock to how you play btw. It'd be exactly the same against me as my UTG 4 bet range is about as narrow as it gets.