Spooks (BBC1, 9pm); Catastrophe (C4, 9pm)

WE’RE here, according to presenter Tony Robinson in Catastrophe, because we got lucky. If things – that’s to say something that happened three billion or so years ago – had gone differently then we, as in Planet Earth, might not be here.

You really have to concentrate to keep up with the Time Team supremo in this new series about catastrophes that shaped our world.

I could only echo what someone says in Spooks, “I don’t understand.”

The person being addressed has little sympathy. “Understanding’s over-rated, just do it”.

Sound advice in Spooks, possibly the best series on TV at the moment. Events are building up nicely to the inevitable cliffhanger climax to the present, and I sincerely hope not the last, series.

Spooks boss Harry now knows the identity of the traitor within (or does he?), having eliminated Connie from his inquiries. The “old team” is intact and busy buying weapons on the internet like other people do their weekend shopping online from Sainsbury’s.

Up for sale is an “assassin’s best friend”

– a piece of high-tech equipment that disables electronic systems simply by looking at them. It certainly saves you getting up to turn out the light.

This is an excuse for Lucas North (Richard Armitage, ably filling the male totty vacancy left by Rupert Penry Jones) to run around glowering and looking efficient as he finds the seller of this piece of classified military hardware is a teenager on a London council estate.

In The Bill, they sell crack. In Spooks, it’s weapons of not-quite-mass destruction.

Lucas and Harry have reckoned without an operative who’s turned nasty and a dead paparazzi photographer, of whom ice queen Ros (Hermione Norris) says perceptively, “I doubt he was killed for clicking someone’s cleavage”.

The Foreign Secretary is on Harry’s back to keep things calm as a vital emergency meeting is being held over the Palestinian crisis. “Don’t let me down, this summit is critical,” she tells the spy boss.

Any holes in the plot are swiftly Polyfilla- ed by the ludicruously fast-paced narrative, the behaviour of the cool as a cucumber spooks and scenes of adrenalin- pumping action.

Back in Catastrophe, Robinson is telling how four-and-a-half billion years ago, the earth collided with another planet.

How does he know? Was he there?

Could they claim on the insurance?

This was the first great catastrophe (the latest being John Sergeant taking an early bath from Strictly Come Dancing) and left the planet “a vision of hell, a barren lifeless place shrouded in toxic volcanic gases”. Sounds like the I’m A Celebrity campsite once obnoxious David Van Day and mad as a hatter Timmy Mallett joined the happy campers.

I’m not sure why Robinson is presenting this series.

He’s not an expert on the subject. I can only guess that he had a gap in his Time Team schedule and C4 didn’t want him hanging around on street corners.

We meet Bill, who has spent his life studying events of the early solar system.

He looks at Mercury and Mars and sees what we were like.

There is talk of cosmic debris, vaporised rock and a climate hellhole (which could be most British seaside towns in winter).

I get the impression there’s a lot of guesswork going on here, in the light of someone saying there’s no evidence from the time of the collision. But they reckon one thing led to another, the collision led to debris which led to planets which led to... at which point I lost both track and interest despite the nice graphics imagining what happened.

“If it had been slightly different, there would be no one here at all,” decides Robinson. “We got lucky in a sense.”