For anyone interested, this is the ICO's guidance on refusing an FOI request on grounds of vexatious requests, which appears to be the exemption that has been relied on here:
ico.org.uk/media/for-organisations/documents/1198/dealing-with-vexatious-requests.pdf
The Information Commissioner recognises that dealing with
unreasonable requests can place a strain on resources and get
in the way of delivering mainstream services or answering
legitimate requests. Furthermore, these requests can also
damage the reputation of the legislation itself.
9. Section 14(1) is designed to protect public authorities by
allowing them to refuse any requests which have the potential
to cause a disproportionate or unjustified level of
disruption, irritation or distress.
Seeking to damage the reputation of a charity doesn't seem on the face of it to meet the bar on this one.
Scattergun approach
The request appears to be part of a completely random
approach, lacks any clear focus, or seems to have been solely
designed for the purpose of ‘fishing’ for information without
any idea of what might be revealed.
Again, this is the quoted exemption but doesn't seem to hold up against the substance of the request, which is for specific information.
I'd be surprised if this one didn't fall at the internal review stage, let alone the ICO.