I went to Abingdon School, which is quite close to Culham labs (JET) in Oxfordshire, in the mid 1980s. One of my A levels was Physics. We had some boffins fro

I went to Abingdon School, which is quite close to Culham labs (JET) in Oxfordshire, in the mid 1980s. One of my A levels was Physics. We had some boffins from JET pop on over and do a presentation to us about what they were up to. I was one of the thickies. Some of my (then) compatriots are now dons and even proper scientists! I only managed a random walk into IT. I dimly recall a graph showing progress on how they were able to fire up the thing and the energy out compared to energy in. That graph had quite a decay on it initially but a really long tail. That long tail is where the always 25 years off meme comes from. Nuclear fusion as an energy source is a massively complicated beast. You might like to note, say, that building for Hinkley Point C (a fission plant, Somerset, UK - just up the road from here) was started late 2018 and was due to be commissioned in 2023 and now is due in 2030. You might also note that aircraft and the like tend to take 20+ years to go from concept to service. A nuclear fusion plant will take quite a while to commission once a concept has been thrashed out. Perhaps CF have got it sorted but there is a damn good reason for the always 25 years off "joke" - I was told it over 30 years ago by physicists working and already long time served at the coal face.