@Frequency,
I would agree with you that Cruelty,pain and fear have no place in dog training with one exception: a confirmed stock-worrier when other training methods had failed. I don't subscribe to death before discomfort.
I'd be interested to know what qualifications the trainers at Southend Dog Training have because I don't know of a single training institute which advocates the use of prong collars or E collars as a punishment.
There are several canine organisations that offer training for trainers and sanction the use of prongs and e-collars. The IACP, for example, adheres to the LIMA training philosophy (Least Invasive, Minimally Aversive) and supports the use of tools as training aids, so long as the dog is not abused in the process.
E-collars used at a low to moderate stim do not cause pain; some don't even when used at their highest setting. I've tried one out on my own skin, and I've seen dogs being trained with them who show no pain or fear. In fact, I have seen less negative reaction to a first stim from an e-collar than to a first try with a halti. They can certainly be badly misused, but so can any training aid, including a lead. It also needs to be remembered that every dog is different. They have different drives and different likes and dislikes. Some dogs would rather endure discomfort than frustration. Some dogs find loud noises deeply aversive and would be terrified of a rattle can, whereas others wouldn't care.
Ultimately, the proof of the pudding is in the eating. I know a lot of people who successfully field trial their gun dogs, some at the highest level (KC Championships), and my dogs and I have been trained by some of them. They have great relationships with their dogs - they all stress the critical importance of building a good bond with your dog. The dogs are happy, confident and secure, and they have all been trained with a balance of reward and aversion.
I'll link again to the podcast I posted upthread. It's a respectful (and sometimes funny) exchange between trainers from different sides of the debate and is 100% worth a listen.
Nando and Jo-Rosie
thecanineparadigm.com/2021/04/04/episode-172-nando-and-jo-rosie/