Whether the insured proved that he filed an appeal against the 4 August 2008 AI decision within the legal time limit.
He did not prove that an appeal was filed in 2008; the available medical certificate did not establish a filed appeal.
The burden of proof for filing lies with the appellant. No archive or file record showed a 2008 appeal, and the later certificate only suggested an intention to contest the preliminary notice, not proof of a filed appeal.