Just to clarify:
Mr Ball instigated a private prosecution against Mr Johnson, alleging “Misconduct in Public Office". In order for that to progress to the Crown Court as it must (as it is an indictable only offence) it must first be presented to the Magistrates’ Court. That court has a duty to examine whether there is sufficient evidence to see the matter progress to trial. If that court makes a finding that there is sufficient evidence a summons against the defendant is issued and the case goes forward to the Crown Court. If it finds there is not, the matter ends there (bar any appeals).
Magistrates’ courts are variously presided over by three “lay” magistrates or by a legally qualified “District Judge (Magistrates’ Courts)” sitting alone. Very often in cases that involve complex areas of law a DJ is appointed and that was so in this case. She ruled that there was sufficient evidence and that a summons should be issued.
Mr Johnson appealed that decision and the judgement provided is the result of that appeal. When an appeal is either against sentence, or against conviction if the decision rests on “matters of fact” or a simple matter of law appeals against decisions in Magistrates’ Courts are usually heard in the Crown Court (before a judge and two “lay” magistrates). However where a more complicated matter of law is concerned appeals usually go before the High Court (Queen’s Bench Division) as in this case. The appeal was indeed brought by Mr Johnson on two grounds: 1. That he was not acting in public office when the alleged offence took place and 2. That the prosecution was “vexatious” (that is, brought with the intention to annoy or harass rather than to cure a mischief).
The High Court ruling overturned the DJ’s decision on the basis that the ingredients of the offence (particularly that Mr Johnson was acting in public offence at the commission of the offence) were not made out. The High Court was not required, therefore to rule on whether the prosecution was vexatious but nonetheless commented that they would have done so as they found the DJ’s decision that it was not was flawed.
Mr Ball (adequately aided by his legal team, natch) seems incredibly keen to continue spend hefty sums of other people’s money. My view is that he has virtually zero chance of his prosecution getting to court. Material from his website (which he deleted but some of which the High Court managed to recover) clearly shows his motives for pursuing his action against Mr Johnson. I expect he has been advised (or at least he ought to have been in the light of the money he has spent on his legal team) but the Attorney-General has the power to take over and discontinue any private prosecution:
https://www.cps.gov.uk/legal-guidance/private-prosecutions
But I doubt his legal team cares whether he heeds them or not. They will continue with his folly until other people’s money is exhausted.