I am in an odd position here as I am the mum of a new Yr7 at WHSG this year and also work for the Local Authority.
The school was unhappy with the intial Ofsted report and the one which was eventually published only appeared after several re-drafts. The school remained unhappy and have formally complained to Ofsted. The Local Authority have supported the school with regard to several of the grounds for their complaint. Ofsted are investigating this, but in the meantime, the report is now in the public domain, with no rider or acknowledgement included that this is in dispute with both the school and the LA.
To add some balance, there were a number of issues raised by Ofsted which the school have accepted as being fair criticism. Whilst not referring directly to these, during parent presentations/meetings at recent open days and induction days, the school have explained what steps and processes they have now put in place to address/rectify these issues. This includes additional monitoring of teaching standards and additional reporting of pupil progress to parents.
I think that it is also helpful to consider what Ofsted reports are about. They are only a snapshot in time and also (as others have stated) only look at a few certain issues. Ofsted are looking for added value - and this can be a harder measure for the grammar schools, when the children going there already start at a higher than average. The added value measure does not represent final achievement - and you will be able to see from the WHSG website that their exam results this year have been very good, with the school still amongst the best in the country when looking at league tables.
However, our main reason for selecting WHSG was not based on Ofsted reports, but rather on finding the right school for DD. Even with higher academic results at CCHS, we felt (and still do) that WHSG is the right place for DD. The non-academic aspects of the school - not considered AT ALL in the Ofsted inspection regime - were (in our view) much more appropriate for our DD that in other grammars. Added to that, the high level of pastoral care, extra-curricular activities, charitable events, school organisation, form structure, house events etc, etc, etc mean that a school is much more than its Ofsted Report!
If you are considering it, do go along and ask questions. Make an appointment with the Head Teacher and don't be afraid to ask direct and hard-hitting questions - to any school you are considering.
Hope this helps - and good luck with your decision. I know only too well how stressful it all can be!