You should look at the other sections of this MHRA forum -- for instance; PI delegating PI duties; Delegation of duties.

The MHRA GCP Guide (2012) states:- In relation to a clinical trial, the term ‘investigator’ in Regulation 2 of SI 2004/1031 is defined as: ‘ the authorised health professional responsible for the conduct of that trial at a trial site, and if the trial is conducted by a team of authorised health professionals at a trial site, the investigator is the leader responsible for that team’. It does not say the PI is the leader responsible for that team unless he/she is put under pressure by their management! GCP inspectors all over the world have issued inspection findings and Warning Letters when a PI is not exercising their responsibilities as the leader of the clinical research team. So I think the answer is self evident.

The MHRA GCP Guide makes it clear that they anticipate that only the PI will delegate duties to their staff (11.3.4) :- "In order to demonstrate that the PI has authorised appropriately trained and qualified individuals to undertake certain trial related tasks, a delegation of authority log is used at the site. This document may be combined with the site staff signature log, but should clearly state the name of the person, their role and the activities they are delegated by the PI as well as being signed and dated by the PI prior to the activity being undertaken by the individual. It is not acceptable for the PI to simply sign-off the delegation log at the end of the trial. The delegation is not just a paper exercise; it is documented evidence of appropriate delegation of investigator’s responsibilities".

RQA (formally BARQA) answered a similar question on their GCP website (www.theRQA.com), about the PI delegating their duty of signing the protocol or alternative contract, to show their agreement. You may find that useful.

If you read the other sections of this MHRA Form you will see that the views are consistent:- The PI should not delegate duties to those who are not appropriate and should withdraw duties from those he/she deems to not be carrying them out according to GCP, legislative requirements and the protocol.