When I tried to request it via ILL, they told me that the amount of material scanned "exceeds copyright law and scanning limits". I haven't bothered to look up whatever law that is, and I'm not sure if it's a US thing, or if it's on the UK side, and if so, whether students/faculty at Cambridge are under the same restrictions and they'd have to end up paying the same fees as well. I have a friend whose advisor works there, but I'm reluctant to ask them for the favour and potentially drag them into numerous back-and-forth emails with Cambridge Library and copyright issues...