Sadly, fans being fans, the episode's attracted criticism for a muddled bit of continuity which might not be muddled at all - namely that The Doctor makes an off-the-cuff remark about having regenerated "half-a-dozen" times since he last saw Sarah, which contradicts "The Five Doctors", which Sarah almost certainly has no memory of. So there you go, New Production Team. Don't try and do anything nice for the series' long-term following, they'll just poke you in the eye.

What really matters is Liz Sladen's amazing ability to slip convincingly back into the role once again. Even counting Downtime, it's a decade since she's been onscreen in the part, but Sladen is never less than 100% convincing. She is Sarah Jane Smith. K9 is superb too. Thankfully a total overhaul hasn't been undertaken, and they haven't even bothered totally silencing the motors or getting completely rid of the little guy wobbling. I defy any fan to say they didn't feel like jumping for pure joy when K9's fending off the Krillitanes in the school hall. Marvellous stuff.

It's not just a nostalgia trip. The Doctor being confronted with his impact on someone's life is a recurring theme for the new series, but here it's handled well, and for once we're given the rough answer - it might never be easy to have an experience like travelling through time end, but after a few years you get on with things, and Sarah Jane's life is certainly all the better for having experienced all those things. Rose's jealousy is also well done, as is the wonderful scene where both characters realise how silly they're being. Following the quasi-soap elements of certain parts of the previous season it's pleasing to see The Doctor sit back and just let them sort it out - he actually seems pretty much oblivious to the tension, instead of making whince-inducing "No domestics!" comments. Mickey is well utilised for once, getting to be a bit useful at times, and Noel Clarke is more impressive when he's not needed to be Comedy Useless Boyfriend. It can't be a coincidence that this happens in his first appearance not scripted by Russell T. Davies.

The setting, while not the most original idea in the world, works well in Doctor Who's format (it might be a poor memory, having not seen the thing for years, but it was a bit reminiscent of the fan video spin-off Downtime, wasn't it?). Could the equation all the children were working on be something that gets returned to maybe? The teachers all managed to be sinister, but I can't help but feel that Anthony Head was rather wasted, being required to do little but hiss a bit and recite stock villain dialogue. In fact, the whole plot struggles a little for space alongside the relationship dynamics... It might be that rare beast, a Who story that really needs another episode so there's space for all the stuff crammed in.. The Krillitanes lacked depth, and their bat forms were a little too similar to the Reapers from "Father's Day". Hopefully Finch will be resurrected at some point, maybe as part of something bigger (it was interesting how he never shape-shifted).

Overall, it's a warm, glowing story which revolves around The Doctor and his present and past companions. The plot is convincing, and it's nice that we get to end on a happy note, with Sarah reunited with the rebuilt K9. His sacrifice was dramatic, and the scene is a little saccharine, but it's indicative of The Doctor's basic desire to leave happy people where he goes. A fine story full of great moments.

Review written: 08/05/2006