Many private providers will try to reduce costs by requesting that NHS GPs carry out tests on their behalf. NHS GPs are not contractually required to carry out tests on behalf of private providers. If a private provider thinks certain tests are required then the responsibility lies with the provider to carry out the tests.
Private providers will also try to reduce costs by performing certain tests and then asking NHS GPs to interpret them. GPs are not contractually required to interpret these tests either and the GMC (General Medical Council) is clear that the clinician requesting a test is responsible for arranging the test and following up the results.