Instead of square brackets, you'll want to use double quotes.
Since this is likely a quoted string of text, the double quotes need to be escaped with the Backslash:
many thanks, this resolved it.
Can you point me at a document that describes syntax for JDBC/FMP in this level of detail ?
I was unable to find it.
Pull down FileMaker's help menu and select ODBC and JDBC Guide from the Product Documentation submenu. That's the only official source that I know of. It does have a number of syntax examples in it.
I come at this info from the other side as I have been experimenting with the new ExecuteSQL function and it uses the same SQL syntax (and the SELECT examples in this same document are valid examples of what to use with this function as well as for ODBC and JDBC...)