Free web forum board

My father has asked me for recommendations for a free web forum board. He says:

My main requirement is that it should be a complete off-the-shelf system which I can sign up to, do a little configuring and away ye go, Jimmy. I have neither the time nor the expertise to download something like pHpBB, find some webspace and set it up. It has to be sign-up-and-go.

I had a long look at InvisionFree but they never answered a simple query so i gave up there. And YahooGroups no longer appeals.

I have no idea about any of this, but he ends:

Ask your friends if they have any recommendations.

so I am.