Some episodes you think, "Yeah, that was fun. I'll watch it again some day." Others you think, "I cannot wait to see that again!"
The Pandorica Opens – perhaps the most epic, pulse-racing Doctor Who ever – is also one of the few Radio Times didn't get as a preview DVD this year, so I've had to be patient between viewings.
Two weeks ago at a Soho screening with six other journos I sat glued to the telly, furiously scribbling notes. An utter scrawl during the last ten minutes!
Then I caught that "final reel" again this Thursday (excused for an hour on a hectic press day) as I hopped on my Vespa across to London's Notting Hill for a thank-you screening for Who's media chums at the Electric Cinema. On the big screen, you truly appreciate how cinematic modern Who can be, despite dwindling BBC budgets.
Afterwards, we heard from director Toby Haynes, a Who first-timer (and childhood fan), who's done a magnificent job. He praised his director of photographer and said how HD cameras using cinema lenses achieve such filmic depth. He revealed they had 45 minutes of daylight plus a night shoot to make the most of Stonehenge; the rest was done elsewhere on "foamhenge" – a mock-up with three stones.
Time and money meant the Cyberman head latching onto Amy nearly had to be dropped, but Haynes reworked the scene and made the FX as physical as possible (rather than CGI), to get it on screen.
"Underhenge" is the biggest set yet built at the BBC's Upper Boat Studios, described in the script as not unlike a temple you'd find in Indiana Jones. Haynes said he actually played John Williams's music on set so the actors rhythmically slowed down and felt the moment as they explored the Pandorica chamber.
The four leads certainly deliver. But top marks to Steven Moffat for packing in surprises and slotting together the season puzzle with a dazzling plot, urgent pace and terrific dialogue:
River: "Everything that ever hated you is coming here tonight."
A stunning shot of spaceships in the night sky above Stonehenge… A bewildering name-check list of aliens from many eras – Drahvins (1960s), Draconians (1970s), Terileptils (1980s)… Then the Doctor is confronted in the Pandorica chamber by Daleks, Cybermen, Sontarans, Silurians, and various other costumes lurking in the store cupboard. As a child, I'd have been wetting myself with delight. As a continent adult, it's pretty gratifying, too.
Rory: "You have to run. You have to get as far away from here as you can. I'm a thing. I'll kill you. Just go!"
The one thing I never saw coming was the Roman centurions being revealed as Autons. A shiver down the spine stretching back 40 years. And just as Amy regains her memory with a heartbreaking, "Why am I happy?", poor sweet Rory or "Roranicus" battles the Nestene influence over his duplicate being – but shoots Amy dead.
Yes, I am told, Amy is dead...
River: "It's a trap. It has to be. They used Amy to construct a scenario you'd believe to get close to you."
In majestic slow motion, we see Amy's dying moments, River battling with a haywire Tardis and the Doctor being hauled into the Pandorica, where the alien alliance will restrain him for ever. As the Sontaran says: "We will save the universe – from you!" Get out of that, Time Lord!
"This is the adventure/awe episode," says Toby Haynes. "Whereas 13 is how the Doctor wraps it all up. How he fixes it. It's like Back to the Future. It's amazing. The weirdest piece of writing I've ever read for TV."
Start the countdown to 26.06.2010…