A tenant has vanished owing me a fairly large amount of rent.

Tenancy Types and Management

A tenant of mine has vanished owing me a fairly large amount of rent. I intend to issue against her in small claims, but as I don't have an address for her (or her ex-husband who also signed the agreement and who I can therefore also issue against) I don't know how to proceed. Should I use a private detective or is there some way of tracking them down using their name and date of birth? I use Equifax for credit checking and there's something on their website about debt collection but their helpline wasn't very helpful.
I was under the impression that you use debt collectors after the court has found in your favour but without an address I can't issue a claim.

Please help!

Regards

Ben Lockett