I don't doubt that Sue Gray knows politics, but given how famous she has become in recent years, her appointment must have been a strategic move designed to advance Labour's objective of restoring trust in politics. Or at least designed to prove that they are a party of government.
However, this has backfired in a couple of ways. Firstly, it gives Boris and his followers a small window of opportunity. No doubt Rees-Mogg, Dorries and the rest will see this as vindication. And unfortunately a small part of the population might be inclined to think the same way.
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Secondly, appointing senior civil servants to powerful political positions does the opposite of restoring trust in politics. Of course it is highly unlikely that there has been any foul play here, but it isn't a good precedent to set. Senior civil servants shouldn't aspire to glamorous party-political careers, where they can quickly jump across when it suits them.
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Of course, those in favour of the move will say that this appointment is brilliant in establishing Labour as the ‘party of government'. Maybe they should also make Kate Bingham Health Secretary while they're at it, and get Alan Sugar to run the Business Department.
Sunak is now also in a particularly strong position, with one of his options being to block the appointment. He could then come out in defence of transparency and impartiality - positioning himself as the figure representing those principles, exactly who Keir Starmer wants to be.
I agree, it seems hard to understand the logic of this given the reactions were predictable and unhelpful to Starmer. It gives the Tories an easy target