I didn't make any claims about SEN provision in the 90's, it's not something I have any knowledge of.
All I was saying is that I have encountered many people with kids who are now at least twenty who have told me they didn't put them in school at age 4, but purposely kept them at home or pre-school and put them straight into year 1 at age 5. I just don't think this was remarkable years ago. I met a lady running a playgroup who put her child (ten years older than mine, then) straight into year 1, because she wanted their language to catch up a bit first. My much younger 30 something brother went straight into year 1, and he was a bang average kid. I have a cousin in their mid 30s who started school in one area at 4 - the family moved - and then had a battle as the new area said they didn't have provision for 4 year olds. Eventually they let my cousin join year 1 early, presumably the school had been satisfied that they were developmentally ready.
My experience of mixing with large amounts of people of different ages and chatting about this sort of stuff tells me that virtually no child goes straight into year 1 today. If kids are starting at age 5, the parents are overwhelmingly wanting them to go into EYFS. And while some schools are fine with that, some are very resistant. And if I had a pound for every time I have heard a parent say 'My child wasn't ready for school at 4...' 😀
My point is, that although children are still not legally required to be in full time, formal education until the term after they turn five - which technically means year 1 - it is now considered unusual, but this wasn't always so.