My DD1 has just collected her GCSE's from her school which is an Essex girls Grammar with high standards. DD1 has done very well and 'likes' single sex teaching (if she wanted to learn with boys she would got to the Boys Grammar for Sixth Form). However, like most Grammar Schools whether Boys or Girls they are Co -Ed or in my DD's School partially with around 30 Boys in both Year 12 and 13. I know this seems to be the fashion that Girls Schools which really should be single sex all through are admitting boys these days into year 12. I guess it is probably due to funding though personally I would prefer single sex availability for girls with the Boys Grammars offering the Co=Ed experience if wanted.