After what seems like an age, Torchwood is back. With a prime-time slot on BBC One every night over the course of next week, the show promises to be bigger, better and bolder than ever. But has it learned from its past mistakes? Here, in no particular order, are the five things we'd most like to see from Children Of Earth...

1. Bring Jack back!

I remember when I first met Captain Jack... He was flirty, he was fun, he was... fantastic. Perhaps it was partly down to incoming showrunner Steven Moffat's writing, but here was a character who I knew I could watch week in, week out, who didn't take himself or the situations he got into too seriously. For this reason alone, I was excited by the prospect of Torchwood, the spinoff show with Barrowman's character taking centre stage. Imagine my surprise, then, when I met Torchwood Jack: angry, angsty... Angel. This new character seemed to owe more to Joss Whedon's vampire with a soul than to anything from Doctor Who, with a bit of Captain Scarlet thrown in for good measure.

You could argue, I suppose, that living for hundreds of years and not dying would have taken its toll on his funnybone, but every time he's returned to the mother series since Torchwood began, he's immediately reverted to the same roguish figure we'd come to know and love during the Chris Eccleston season. So where is he now? One can only hope that he made the trip back to Cardiff from that anonymous Ealing park (I'm assuming it was Ealing, since Sarah Jane was the first one to leave) with his sense of humour intact. Besides, with dreary Owen and Tosh no longer around to drag him down, he's got to have something to smile about, right?

Okay, so he's still got emotional vampire Gwen, but he's also got his Ianto. Jack should be in a pretty good place right now, by all accounts. The bottom line is, Torchwood needs the Captain Jack Harkness who saved the Earth while riding on the back of a German bomb in the middle of the Blitz, not the one who spends all of his spare time in his office and never sleeps. Bring that Jack back, and Children Of Earth surely can't fail to find its audience.

2. Less Cardiff, please

Don't get me wrong; I like Wales as much as the next man (unless the next man happens to be Anne Robinson), but setting all of Torchwood's adventures in or around Cardiff has always felt like a bit of a missed opportunity to me. There's so much potential in the idea of an Earthbound alien defense team, denying the show an idea of scale that would give the viewers the sense that what Jack and Co. were doing in some way made a difference to the wider world. Even at the end of the first series, with the rise of Abbadon, a giant monster who brought death and destruction to all who fell under his shadow, it all came down to a confrontation in a field just outside of Cardiff. Last year's radio play, Lost Souls, despite having many faults, did a good thing in taking the team off to Switzerland. And the Master sent the team off on a wild goose chase to the Himalayas. It's clear that the team has a reach outside of Wales, so why don't we ever see this on screen?

I recognise, of course, that the show is on a limited budget, that RTD wanted to do a show set in Wales, and that there's a giant rift in time and space that needs looking after. But I'm not asking that the team go on a weekly field trip, nor that the show turn into a cheaper clone of Doctor Who; neither of these things would be at all beneficial or true to the show. I would just like to feel, especially with a big five-part story airing on primetime BBC One, that the threat to Earth this time extends beyond the Severn bridge...

3. Give Ianto a character... Any character

The presence of Ianto Jones in Torchwood has always been something of a mystery to me. During the show's first series, he was little more than the team's butler, playing only an incidental role in proceedings (apart from when he was tending to his cyber-girlfriend in the basement, or doing something unfathomable with Jack and a stopwatch).

The second series saw Ianto being allowed out on the road with the gang, but his role within the team seemed to have been reduced from butler to maker of the occasional comic quip, essentially the Torchwood equivalent of Scrappy Doo. As the series drew on, I increasingly found myself wondering: What point Ianto Jones?

The writers felt that the best way to address this problem was to have his relationship with Jack progress from stopwatch fun to something a little more intimate, but even then I had trouble caring; I had no clue who Ianto Jones was. Frankly, I still don't know; his brief appearance in Doctor Who taught us that he likes watching the Paul O'Grady Show, and I'm guessing he still has his stopwatch, but that's about it.

Of all the characters on the show, Ianto is the one most in need of some serious development. At the end of Series Two, the production team took the bold move of killing off 40% of the regular cast, with Ianto among the survivors; can he really prove as valuable to the team (and the show) as the much-liked Tosh, or the less-liked Owen? And just who is Ianto Jones, anyway? We can only hope that Children Of Earth holds the answers.

4. Give the team a proper villain to face

A problem that Torchwood seems to share with its parent programme is that there's a distinct lack of strong evil figures. Both shows contain all manner of threats, from Daleks to Weevils, from Toclafane to alien sex gas (am I alone in hoping for its return? Day One was clearly a splendid piece of television), but when it comes to strong, personified villainy, the production team seem reluctant to commit themselves. Could it be that they're still too afraid of creating another moustache-twirling caricature, like Anthony Ainley's Master?

This isn't to say that Torchwood's been totally bereft of villains, mind - Bilis Manger in Series One was a toe dipped in the water, and one of the few aspects of that first run of episodes that people still talk about in a positive light; he's even made at least one reappearance in the novel range. Captain Spike, sorry, Captain John Hart in the second series was another step in the right direction, with James Marsters joining the cast for some truly memorable installments in the Torchwood saga.

Here's the thing: people always remember the villains. Long after Luke Skywalker and his friends have disappeared into the great beyond, the ominous shadow of Darth Vader will continue to loom large over our collective consciousness. And why is it that Moriarty, who appeared in more episodes of Star Trek: The Next Generation than he did novels by Conan Doyle, is almost always mentioned whenever the topic of Sherlock Holmes comes up?

At heart, we all love the evil characters; there's something appealing about their complete lack of morals. What's more, writers enjoy writing for these figures, almost as much as most actors want to be the one who gets to play them.

In short, a well-written baddie who is central to the proceedings will make everyone up their game, and could make the difference between an average story and something truly special. But with Captain John seemingly on the road to redemption, and the show's other hate figure, Owen Harper, pushing up the daisies, who will be Torchwood's next Big Bad? With luck, we'll know by the end of this miniseries.

5. Bring them into the Whoniverse

The Doctor Who episode Journey's End, as well as being a fitting end to RTD's time on the show (I can only wonder how he's going to top it with the Christmas specials, but that's an issue for another time), gave us our first proper impression of a truly integrated 'Whoniverse'. For the first time, we could really grasp the idea that Torchwood and the Sarah Jane gang exist in the same reality, on the same Earth, with the Doctor occasionally flitting between the two. We saw UNIT, former Prime Minister Harriet Jones, and an Earth that is starting to get used to the fact that aliens like to invade from time to time.

Well, now it's Torchwood's turn to pick up the baton. With the exception of Martha's stint on Torchwood last year, the show has always felt detached from the rest of its brethren, with any occasional references to the parent show being euphemistic at best (the Doctor wasn't referred to by name until Fragments, near the end of the second series). This was perhaps understandable for a show looking to attract its own, adult, audience, but with the show now a part of Who lore, it's time for them to start acting like it.

I'm not suggesting that the Doctor should show up, or even Mickey or Martha (for me, Martha stuck out like a sore thumb when she visited the Hub last year); leave that kind of thing to the team on Bannerman Road. But there's no reason not to get UNIT involved, and a planet-wide emergency like the one I'm hoping for would simply have to involve newsreader Trinity Wells, surely?

But if Children Of Earth really wants to cement Torchwood's place in the Whoniverse, then it needs to do something radical, something which will change the shape of the world these characters inhabit for years to come. Kill off a percentage of the population, disband UNIT. Do something daring that will have a greater impact than just the occasional reference, and you'll ensure that the show goes down as more than just a footnote in the history of the franchise.

Oh, and one final note to the production team: bring back the pterodactyl, will you? You can't introduce the incredibly cool idea that you have a dinosaur living in the roof and then spend two seasons not showing it! Will Myfanwy become a fully-fledged member of the team now that Toshiko and Face-Ache are gone? Tune in and find out...

Torchwood: Children Of Earth starts on Monday 6th July at 9pm on BBC One...