I thought the precedence was the other way, that enquiries receive ‘self-selected-relevant-material’ e.g Chilcot.
I think this is more significant as it is a result of the breakdown in trust between the Establishment/Civil Service/Judiciary and the government. Normally, they would be trusted to hand over all the relevant material but not this time!
Almost certainly a protest vote against the congestion charge plans for the city that have been introduced by Labour/LD rather than anything pertaining to national party matters.