Hi Northern Rose
I think I know what you are looking for.
There are some local history books about Altrincham that refer to Oldfield House the school you are looking for. However I've found the following site that gives quite a good summary of the history. The site is in fact a property developer's but I have absolutely no connection with them

What they have done is develop the school which replaced Oldfield House. You will see reference to it in the article.
http://www.holland-hall.co.uk/pdfs/simplygeomagazine/simply_geo_issue_3.pdfTo locate it go to
www.old-maps.co.uk and key the coordinates 375600 38840
This should bring you on top of Oldfield Brow. Enlarge the map and you should see the text Oldfield House.
I think the blurb from the above gives the PostCode of Blakeswood. You could use it to find the replacement school on
www.streetmap.co.uk and whee the old school was.
I hope alll this makes sense. However if it doesn't and you cannot find anything let me know .
Regards
Reiver
PS There is/was an Oldfield Hall. This is not what you are looking for
