The subjunctive!
It is essential he ATTEND/ATTENDS the meeting.
I demand he GO/GOES now!
Most Brits would use either form, and not notice the difference. I suppose if one wanted to sound more formal, one might choose the subjunctive. In an exam one should go with the subjunctive (better safe than sorry!).
I gather that Americans nearly always choose the subjunctive. Now, here in England, if someone chooses the 'incorrect' form in a grammatical structure the user may sound uneducated. I don't want to get into an argument here about regional/colloquial English, and social class - so try not to consider that aspect please!! My question is.... DOES A BRIT WHO SAYS, "IT IS ESSENTIAL HE GOES TO THE MEETING" sound uneducated to an American?
Often we sound a bit quaint and old-fashioned to Americans, I think. Perhaps we often sound 'correct.' But in this case of the subjunctive is it Brits who sound... just plain wrong?
I attach links to feisty discussions on this point:
http://www.antimoon.com/forum/t16622.htm Do Americans ever NOT use the subjunctive?

