Go to Registry Trust and see what he has against him- make sure your CCJ is there, this is then evidence you can let the client know about it
REGISTRY TRUST LINK
You have a duty to make your client aware (hand them the report from Registry Trust and let them make their mind up- then you have informed them)
If things were to go pear shaped with the joiner with the client and it came out you could have told them this it may be awkward for you.
You could also get the RT info and do a leaflet drop with it
Can you check if he owns his van through DVLA and HPI check- if he does then you can have a baliff seize it to expedite payment.
Do they own a property? Add an inhibition - you will get interest ay 8% per annum