Look at all the schools in the area/legue tables and decide which one you think is "excellent"
Then make sure your child practises for the 11+ they wll need to pass to get into the grammar school (you can buy past papers from WHSmiths and similar, though make sure you get the correct paper e.g. multiple choice and the areas that they will take such as verbal reasoning/ non verbal reasoning, maths, English etc)
Usually the "excellent" grammar schools have a high application, so to ensure your child gets into the school that you wish they really must practise hard and ensure they know what to expect and how to do certain types of questions (especially verbal reasoning as many of the questions are similar and you need to learn how to work them out rather than actual knowlage)
Stafford Grammar School was created in 1982.
Minchenden Grammar School ended in 1984.
Herchel grammar by far!!!! OBVIOUSLY!!
Hipperholme Grammar School was created in 1648.
Reigate Grammar School was created in 1675.
Swanage Grammar School ended in 1974.
Bexley Grammar School was created in 1955.
Fitzmaurice Grammar School ended in 1980.
No, it is a high school in a grammar school area.
Queen Mary's Grammar School was created in 1554.
Nunthorpe Grammar School ended in 1985.
Llandysul Grammar School ended in 1984.