Hello, I have been a swim teacher a long time in Cambridge, so I thought I would add my two cents to this conversation.
By far the most important thing in finding good value swimming lessons, where the kids actually progress is recommending and seeking specific teachers, not swim schemes.
The quality of teaching almost always varies considerably within the same swim scheme, since the managers rarely care about the quality of teaching.
At the swim school where I work, there are teachers who can teach children to swim in a fun way on their own, within a few weeks. Yet there are other teachers who have zero interest in teaching at all, where the children do not progress for years.
Please try and steer this conversation towards recommending teachers, rather than swim schools.
For example, rather than saying:
"ESA was amazing for me, I would totally recommend them"
It is much more useful to say:
"John from ESA was amazing for me, he taught my child to overcome his fear of the water and swim 15 metres on his own on his front and back within the first 5 lessons."
ESA does on average have slightly better swim teachers than everywhere else, but it still varies considerably.
Furthermore, never listen to statements from companies saying how good their teachers are, and remember it is easy for companies to leave fake reviews on websites like this.
Sorry to bump up an old thread like this, but it was the first result from google about swim schools in Cambridge, and the information I just provided is absolutely vital to any conversation about swim lessons.