ruggief, ask your Agent what other information they have on the tenants. If they've done a proper credit check then they will have details of the tenant's employers and possibly other details. We don't use Agents but have an 'application form' which asks for NI number, car registration etc. It's not infallible but does make the tenant think twice about doing a midnight flit as we have a lot of info about them.
I'd ask the Agent to supply all the credit check information that they have, and see what you can glean from that.
Good luck.