The dip is normal as grades (especially teacher assessed ones) are sometimes overinflated - the same can happen at the end of year 9. There are obviously other factors that cause the dip. If the levels are from tests, the children sometimes do better because they are coached to within an inch of their lives because so much rides on the grades. However, the children might not retain the stuff they have learned, causing levels to drop in year 7.
However, I would have expected a dip at the start of year 7 but a child to have at least caught up by now.
Do you have any work from the primary that the new school could look at to see if they think its nearly a 5 or if it was inaccurately marked. Also find out what you can do to help him.
I'd be concerned, a child on a level 3 at the end of year 7 will struggle to get a C at GCSE. I'd certainly be asking the school what support was available or what they would suggest to help him improve.
PS I was quite taken aback by the almost-5 in English - it really didn't tally with what I expected as although he's a pretty good reader, he doesn't like books or writing and his handwriting is shocking. His spelling is pretty dire, too.
How worried (if at all) do I need to be that ds has been given a 3.8 for English?
This is almost a full level below what he was given in his SATs (apparently he just missed a 5).
I know they were coached and that there is often a discrepancy between KS2 and KS3 but any assurance or otherwise would be much appreciated.
The rest seem fine btw. This is the lad who was graded (by school, obvs, in SATs mocks) 3a in maths at the end of Y5 but a 5b in his actual Y6 SATs (which has remained static in Y7 - again, not terribly worried - they don't progress in straight lines).