I love the playfulness between the show's main trio. This is playtime for adults. Whilst the characters are top notch and there is still plenty of momentum in this new series, this was a pretty average story and did feel like filler.

The Sontarans are excellent fun but I don't think they have quite had their stand out story yet. I'm hoping their fourth appearance will provide that. Whilst they are visually striking in The Sontaran Experiment it is notable that they actually look worse than in The Time Warrior. I wish they had the original detail around the eyes in particular. None of this is a huge shame as the final product is fine. The torture scenes were quite ingenious and not nearly as gruesome as they sound. I liked the idea of the Sontaran testing human's capabilities.

It was quite strange to see a story completely based on location, there is a lot of potential in this - but as it was set exclusively in a field this was a visually weak couple of episodes. One or two sets it would have added some variety alongside the grassy knolls. I don't imagine the visitors to Earth were just sleeping on the ground, they must have been staying somewhere off screen.

I complained about Sarah Jane being patronised in The Ark in Space and we get a little more of the same here, but in fairness to Robert Holmes I am finding she typically ends up being presented as being correct when her counterparts are wrongly dismissive.

There is some more brilliant dialogue, but given how exceptional these characters are it does feel like an odd placeholder story which wastes our casts great abilities. Its certainly not a bad one though!

Acting as a break between the two Nerva Beacon stories The Ark In Space and Revenge of the Cybermen, The Sontaran Experiment is another one of those odd classic series stories like The Edge of Destruction that form only two episodes rather than at least four. This two parter is the very definition of 'filler'. It feels as though it's just there for the sake of being there.

The Sontaran Experiment follows Sontaran Field Major Styre experimenting on a bunch of astronauts who were brought to a deserted Earth by a fake distress call. The story is badly paced throughout and very dull to watch (something I hate saying about a story from my favourite show). The Sontaran in question doesn't even appear until the end of episode one and even then he never feels like much of a presence or threat to any of the characters. There's not enough story to fit 45 minutes; if anything, it would have been better as a single 25 minute episode as that's all there's enough plot for. At least The Edge of Destruction had more story to it. This one's like it was cobbled together because they suddenly realised they needed two episodes between the previous and next four parter.

The Sontarans are usually great villains but here Field Major Styre feels as though he's only there as a cheap option as they already had the costume made from The Time Warrior. The Sonataran presence really isn't justified; it could be any monster there and it wouldn't make much difference. The only neat thing about Field Major Styre being the antagonist is how it links in to Sarah Jane's first appearance meaning there is history between the companion and the alien race. That's one thing another monster wouldn't have provided.

Speaking of Sarah Jane, Elisabeth Sladen is brilliant and it really shows why she's still arguably the most iconic Doctor Who companion after K-9. In fact, if there's any saving grace for this serial it's the cast. All are on top form, from Tom Baker as the Doctor to Ian Marter as Harry Sullivan. They nearly make it feel like you haven't wasted time watching this serial. It's a shame director Rodney Bennett lets them down however with his poor direction. Everything feels a little amateur and due to the positioning of the actors by Rodney every shot feels bland. There is nothing engaging about the directing in this serial and with a weak story it really could have benefitted from some great direction.

Overall, The Sontaran Experiment is a dull 45 minute story with poor direction, a bad pace and a pointless use of a Sontaran villain with Field Major Styre. It does, however, contain great performances from the TARDIS crew of the time Tom Baker, Elisabeth Sladen and Ian Marter.

A pretty inoffensive two-episode story. It's a nice change of pace to get the rare story that's filmed entirely outdoors in some scenic rocky terrain. The first episode doesn't do much with us meeting some stranded astronauts with a machine following them. It picks up more when we meet the Sontaran, but the story consists of a lot of 'Sontaran pops up with these characters, then with this characters, etc'. The Doctor tiring out the Sontaran is pretty fun. Overall, an inoffensive story but nothing memorable.

Not a ton happens in this episode to be honest, but its short and nice to see Sontarans again

We get some nice background information about humanity during this period, while the Ark was still in space humanity spread out to different planets and survived whatever it was that ruined the Earth

• I rather enjoyed this story, a much improvement on the Sontarans after their first story
• Sells completely how much I like the pairing of Sarah Jane and Harry, if only Harry had more
• I wished the experiments were explored more, the fear experiment was particularly something I wished they explored more
• As much as the story perfectly fits only 2 parts, I would have loved it if we got a third-party
• I often think the side cast takes over, maybe one or two less of them would have been beneficial to smooth the whole story out