I S Backdating

Have a client with mental health problems, he was advised in Oct 2009 may have entitlement to IS but shortly after had a breakdown and suicide attempt. He forgot about making claim until he saw the same organisation in summer 2010 who again told him he should make a claim.
Client was referred to us to assist him with this and a claim was finally made on 4/10/2010. Client thinks claim should be backdated for 3 months before 4/10/10, and has appealed this under reg19(5) of social security (claims and payments) reg saying he was too unwell to obtain assistance in making a claim.
Not sure about the periods of time which have lapsed and client has clearly had periods of time when he has been able to seek assistance from advice agencies. Any suggestions of what I should do to give him any prospect of success at appeal?

The relevant regulation has two parts to it. First that he was too ill at some point in the backdating period. Second and most importantly, that after he recovered and was able to seek assistance to claim, he did not unreasonably delay seeking that assistance and making the claim. To advise him you would need to establish the facts relating to his illness and recovery and the timescales involved.