Agree there are various processes - I was just mentioning some safeguards use by business - rightly or wrongly. I have sympathy with both sides of the scenario as long as it is a balanced and sensitive approach.
One bit of advice after 6 years trying to get a job. An agency that knows and puts you forward is good news. However having recruited - and today I notice I am being cynical - they always have a reason so beware.
My advice after disclosing to the agency is get them to inform the business and say you are willing to provide further details at interview if you can be assured the disclosure will remain confidential i.e. knowledge limited to HR only, and that the disclosure is discussed in a sensitive environment.
If the business will not ensure those bits then I would have concerns about working for them.
Ensure you do not make yourself a victim at an interview by only disclosing the right amount to make them feel secure. They do not have to know all the details of your offence - it is better to give them details of your rehabilitation and improvements you have made to yourself.
Good luck in your search and always here if support can be given.
Learn from yesterday, live for today, hope is for tomorrow else what is left if you remove a mans hope.