Would say both DCs in top half dozen or so of their class in state primary but we didn’t start seriously on 11-plus work till year 5.
Sure, probably need to be fairly bright but the issue we found, at least in state primary, was that the level you needed to reach to be able to compete with more heavily tutored DCs and/or privately educated DCs was, for DC1 at least, beyond what was then being taught in state primary. He needed a good grounding in year 6 stuff before he was formally taught it, as well as being very confident with everything in year 5.
Tiffin, in particular, now sets some fiendish problem solving questions in the latter part of the second round maths paper that a good number will struggle to answer. And without making DCs’ life miserable, it’s hard to know how to prepare for everything. Certainly we tried to avoid that.
Much will simply depend on the day. Put a DC in a freezing cold Tiffin gym on an October morning where the heating doesn’t work and he might not do as well as another similarly able DC sitting in the dancing studio. Equally, luck of the draw on questions - some DCs prefer story writing to writing a letter. In general, though, Tiffin has become a little easier to get into in recent years as year 7 numbers have increased (to 180) - the cut-off score (after going through the waiting list) has fallen. And KGS is mixed, so only 55 places in year 7 for boys. Although the Hampton exam might be harder, it might not be harder to get into as there are more places up for grabs. And it’s a great school (even if we chose, for our own reasons, KGS for older DC over Hampton, Tiffin and KCS).