PHD student on ESA. Can they undertake permitted work?

I have a Part Time (21 hrs per week) PHD student who is in receipt of old style contributions based ESA. They also receive a stipend payment for their studies.

I’m trying to understand whether this person could undertake permitted work without any impact on their benefit payments.

Any advice or suggestions gratefully received.

Thanks.

As far as I’m aware the PhD stipend is disregarded for ESA Conts as it is not mentioned anywhere as relevant income. That being so your client will be able to undertake permitted work with the normal allowances. If you have the time to scroll through the guidance ......
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/932377/dmgch51.pdf

Thanks UB40, really appreciate the info.