Basic Rule: English authority is "Neville v Kelly" stated obiter that an offer of a reward can be claimed for even if the offeree did not know about it.
AO2: This was severly criticised by judges and critics alike, therefore we follow Australian authority.
In the case of "R v Clarke", information was given which lead to the conviction of a murderer, but he forgot about the reward. It was held that he wasn't entitled to the reward.
AO2: This is rather harsh and unfair as the defendant forgot about the reward. Forgetting about a reward is like never knowing a fact.
However, if a party knows about a reward, but has a different motive, they can still claim for their reward. This can be seen illustrated in the case of "Wiliams v Cowardine". In this case information was given to clear the conscience of a woman who thought she was dying. It was held that she was still entitled to the reward. The fact the claimant had mixed motives was irrelevant.