Year 1 DS used to have 2 good friends in his class - the three of them tended to play together and other children joined in on and off. One of the friends has now left the school. Without his calming influence (I presume!) DS and the remaining friend seem to be on a constant rollercoaster of being best buddies, falling out, not talking to each other and then being friends again (am sure this is common at this age!)
But ... when he and best buddy are at a "not liking each other" stage it effectively leaves DS without a friend in his class. He is good friends with a group of 6 other boys and tends to play with them (as well as best buddy) at playtimes and sit with them at lunch but ... they are all in the other Year 1 class.
So ... how important is it to have a friend in your own class? I would have tended to say not (as what they do in class is largely prescribed), but some days DS comes home thoroughly despondent and moaning that he "has no friends".