I was chatting on the phone with my best friend from University who use to tell me how high the standards where at her school in the 80s and 90s (Skipton Girls High) . She was therefore shocked to be informed that entry to their sixth form only requires 5 grade 4s for a Grammar schools sixth form. These are not really the grades expected for someone who passes the 11+ .
I had a inquisitive look at other Grammar schools Sixth Form requirements, Lincolnshire Grammar schools in general for 16+ entry are not onerous.
I know requirements for different schools are a mixed bag, my three children's Grammar schools in Essex require at least 3 7s or (A) grades in old money.
However, in general is passing the 11+ more onerous than achieving so 4 or 5 6s GCSE (B) grades at 16.