However, when I look at the data content in SQL Developer, or when I then perform a 'select' on the table to extract the data later, it has enclosing quotes i.e. I don't get " CONTENT " - I get " 'CONTENT' ", which then interferes with string matching downstream. What have I missed?

You don't need both ->quote and placeholders (?, ?). Placeholders are The Right Way, so just use only those.