Hi, I’m a writer who was previously represented by a (wonderful, well-regarded) agent who did not sell my first novel and didn’t connect with my second. It happens. We parted ways and I’m querying my third. But that’s not the question.
I recently discovered that an old friend of mine and I are writing in the same genre, and I am critiquing his novel for him. I’m almost done and it’s getting to me that this is a book that has quirks that seem to really fit in with what my former agent seemed to like, in terms of her list. I will absolutely recommend that he query her, but should he say it’s on my suggestion? We parted on good terms, but does it matter to say “your former client said you might like this?” FWIW, we parted ways over a year ago. I don’t know if it will be a help or a hindrance, but I really do think I know her interests enough to think that she might really like this book.
In my opinion, that’s absolutely a referral I’d want to get. In fact, you may even want to give your former agent a heads-up that the query is forthcoming, so she knows to keep her eyes on her query pile. A referral from a client, even a former client, automatically moves a query from the slushpile to my “give it a closer look” pile. Good luck to your friend!