Great use of the public purse? One publicly funded authority defending themselves against another one. Whilst you might think Hackney Council lost, really the tax payer did as they paid for both sides to fight.
Completely fair of TfL though to not show any favouritism, they are happy to take anyone's money.
Going to the tribunal to argue the discount is a waste of time as the adjudicator must apply the law & not use discretion. Hackney would have opposed such an argument if used against them.