Hi Sue,
Concord - no e - is a suburb to the west of the City of Sydney on the southern side of the Parramatta River and is next door to the site of the 2000 Sydney Olympics.
Concord was proclaimed as a municipality on 11th August, 1883 so it would have been well established by that stage
The Concord Heritage Society has a web site at
http://www.concordheritage.asn.au/The suburb of Concord now comes under the Local Government area of Canada Bay.
http://www.canadabay.nsw.gov.au Go to the Library, then Local Studies where you will find an email link to the Local Studies Librarian.
The aerial photo on the website shows the suburb of Concord in the top middle of the photo between the two waterways.
I live in Sydney and am happy to help if you have any further questions.
Best wishes
Helen