It was look and say in my 80s primary - and here in wales the lack of direction from welsh government to use phonics leaving methods more up to schools is blamed for the PISA low reading scores compared to England.
My Dsis 5 years younger got a student teacher who used phonics and she had much fewer reading and writing issue than us older kids. DC primary in early 2010 in England was still using mixed methods - while paying lip service to phonics.
I thought it was around 80% of kids not explicitly taught phonics tend to work out the underlying patterns - but quick google suggest it around 40% of kids who can be taught reading with any method - and rest need some explict phonics teaching.
I think research suggest that phonics teaching help 99% of kids understand the code. Once you get past reading - spelling is opposite encoding not decoding and phonics helps there as well.
I think I partially had phonic code - two or three letter sounds being an issue till I taught my DC. Does that mean I struggle to pronounce unknown words - well yes and have been mocked for it. I often encounter new words reading and understood what they meant but pronouncing them correctly wasn't guaranteed. Despite extensive phonics support at home see this with DD1 as well and both of us have been tested and diagnosed as dsylexic.
Nonsense words test in Y2 was to find the kids who haven't grasped phonics - though DC first primary school in England had last minute home work fest to get kids past it. Some kids who could read did fail it at their school.
Look and say arrived in UK in 20s apparently but became most common reading method in 40s and dominated - with 70/80 doing a version with word context heavily thrown in- till 2006 in England when phonics was mandated.
How much if any phonics teaching any adult in UK got I think is very hard to actually say - as even if they had none in school they may of at home or in reading support groups - or they may have had none at all but be in that 40% that learns to read with any method. But I don't think you can assume all adults had some phonics teaching - I don't think I did and had to muddle and struggle through with my own coping mechanims teaching my own DC phonics certainly gave me more tools to use.