I think a certain amount of academics in Early Year (i.e.. nursery and reception year) is probably mildly beneficial--that said, if the UK delayed all academics until Y1, it probably wouldn't be a disaster.
However. While I don't think it's essential to teach actual "academic skills" during Early Years, I DO think that children MUST be learning "pre-academic skills" during those years. So that they are really, really ready to learn efficiently and effectively from Year 1 onwards.
By "pre-academic skills," I mean stuff like:
Understanding the idea of schedules
Learning to sit at a table properly and grip pens/pencils correctly
Learning how to listen to a teacher's instructions when necessary
Learning how to focus on difficult tasks, and how to keep going with something that seems a little difficult or boring at first
Learning to have drinks and snacks at appropriate times and not sip/graze all day long
Developing LOTS of rich vocabulary and general knowledge, through constant exposure to content-rich teacher talk, lots and lots of story-time, and educational trips/outings
Some preschools/reception years are no doubt doing a good job of teaching these "pre-academic skills."
But I do feel like a lot of Early Years practitioners are being encouraged to take the "child-led" idea to a ridiculous extreme--classrooms with activities scattered around them and children allowed to spend all day ricocheting around, choosing what activities take their fancy.
SOME of the day should, absolutely, be spent on free-flow play, but I think it is very important that a large portion of the day is also spent doing adult-directed activities to expand children's knowledge/vocabulary and skills. Some EY classrooms don't seem to be doing this.