It was by the writer of the recent Wide Sargasso Sea, and the director of the Life on Mars 'IRA' and 'Wife Swap' episodes.
I think the trailer at the end had extracts from several different future episodes, but it gave me a massive thrill. I wished they had let Jacobi play Shakespeare, though I suppose he's too old now. It has to be treated like a big deal, and then it is a big deal. And John Simm - he will be a great Time Lord.