Police investigated the armed robbery of a bank, and determined that Fred was the leading suspect. They obtained a warrant to arrest him and another to search his house. When they went onto the property, Fred fired several shots from a high-powered rifle into the air but was quickly subdued and arrested. Constables Harriet and Sam went to a neighbouring house "to check if everyone was OK and no one had got hit". When they knocked on the door they heard what sounded like cries of pain. They shouted "Are you alright?" The response from inside was, "I'm OK - leave me alone." Feeling suspicious, they forced their way into the house, and found Mike - suffering from a minor bullet wound - and also clothing matching that used by the bank-robbers and bundles of banknotes which were later identified as part of the proceeds of the robbery.

Assume Mike was tried together with Fred on charges of robbery. Mike applied for a separate trial but this was denied. He gave evidence that he had been involved in the robbery but only because Fred had threatened to 'smash his face' unless he took part. Despite this evidence, he was convicted. In her reasons for finding him guilty, the judge said that she did not believe him but that, even if Fred had threatened him, this would be irrelevant to his liability because he could have sought the help of police. Mike wishes to appeal his conviction. Explain on what grounds he might appeal.